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1
Zdziennicka, Anna, Katarzyna Szymczyk, and Bronisław Jańczuk. "Wettability of Quartz by Ethanol, Rhamnolipid and Triton X-165 Aqueous Solutions with Regard to Its Surface Tension." Colloids and Interfaces 7, no. 4 (2023): 71. http://dx.doi.org/10.3390/colloids7040071.
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The wettability of quartz by different liquids and solutions plays a very important role in practical applications. Hence, the wetting behaviour of ethanol (ET), rhamnolipid (RL) and Triton X-165 (TX165) aqueous solutions with regard to the quartz surface tension was investigated. The investigations were based on the contact angle measurements of water (W), formamide (F) and diiodomethane (D) as well as ET, RL and TX165 solutions on the quartz surface. The obtained results of the contact angle for W, F and D were used for the determination of quartz surface tension as well as its components and parameters using different approaches, whereas the results obtained for the aqueous solution of ET, RL and TX165 were considered with regard to their adsorption at the quartz–air, quartz–solution and solution–air interfaces as well as the solution interactions across the quartz–solution interface. The considerations of the relations between the contact angle and adsorption of solution components at different interfaces were based on the components and parameters of the quartz surface tension. They allow us to, among other things, establish the mechanism of the adsorption of individual components of the solution at the interfaces and standard Gibbs surface free energy of this adsorption.
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Cronin, Stephen B. "(Invited) In Situ spectroscopy of Electrocatalytic and Photocatalytic Interfaces." ECS Meeting Abstracts MA2024-01, no. 35 (2024): 1980. http://dx.doi.org/10.1149/ma2024-01351980mtgabs.
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We explore various aspects of electrochemistry and photoelectrochemistry using in situ spectroscopy of electrode (metal) and photoelectrode (semiconductor) interfaces in situ under electrochemical working conditions. These spectroscopies include sum frequency generation (SFG), transient reflectance/absorption spectroscopy (TAS/TRS), and surface enhanced Raman spectroscopy (SERS). Using surface enhanced Raman scattering (SERS) spectroscopy, we monitor local electric fields using Stark-shifts of nitrile-functionalized silicon photoelectrodes.6 We also report several spectroscopic methods for monitoring local electric fields (within the double layer), local pH,1 photo-induced surface potential and charge transfer2 at electrode surfaces using surface reporter molecules. The Figure below illustrates two surface reporter molecules for determining the local pH, local surface potential, and charge transfer at electrode and photoelectrode surfaces. We also measured the stacking dependence and Resonant interlayer excitation of monolayer WSe2/MoSe2 heterostructures for photocatalytic energy conversion.3 Using sum frequency generation (SFG) spectroscopy, we measure the voltage dependence of the orientation of D2O molecules at a graphene electrode surface, which is related back to the “stiffness of the ensemble”.4 Using transient absorption spectroscopy (TAS), we measure the lifetime of hot electrons photoexcited in plasmon resonant nanostructures.5 Using transient reflectance spectroscopy (TRS), we measure the photoexcited carrier dynamics in a GaP/TiO2 photoelectrode, as well as the electrostatic field dynamics at this semiconductor-liquid interfaces in situ under various electrochemical potentials.6 Here, the electrostatic fields at the surface of the semiconductor are measured via Franz−Keldysh oscillations (FKO). These spectra reveal that the nanoscale TiO2 protection layer enhances the built-in field and charge separation performance of GaP photoelectrodes.7 1 Wang, Y.Y., et al., Measuring Local pKa and pH Using Surface Enhanced Raman Spectroscopy of 4‐Mercaptobenzoic Acid. Langmuir, DOI:10.1021/acs.langmuir.3c02073 (2023). 2 Li, R., et al., SERS Detection of Charge Transfer at Electrochemical Interfaces Using Surface-Bound Ferrocene. The Journal of Physical Chemistry C, 127, 14263 (2023). 3 Chen, J., et al., Stacking Independence and Resonant Interlayer Excitation of Monolayer WSe2/MoSe2 Heterostructures for Photocatalytic Energy Conversion. ACS Applied Nano Materials, DOI:10.1021/acsanm.9b01898 (2020). 4 Montenegro, A., et al., Field-Dependent Orientation and Free Energy of D2O at an Electrode Surface Observed via SFG Spectroscopy. Journal of Physical Chemistry C, 126, 20831 (2022). 5 Wang, Y., et al., In Situ Investigation of Ultrafast Dynamics of Hot Electron-Driven Photocatalysis in Plasmon-Resonant Grating Structures. Journal of the American Chemical Society, 144, 3517 (2022). 6 Xu, Z.H., et al., Direct In Situ Measurement of Quantum Efficiencies of Charge Separation and Proton Reduction at TiO2-Protected GaP Photocathodes. Journal of the American Chemical Society, 2860-2869 (2023). 7 Wang, Y. and S.B. Cronin, Performance Enhancement of TiO2-encapsulated Photoelectrodes Based on III–V Compound Semiconductors, in Ultrathin Oxide Layers for Solar and Electrocatalytic Systems. 2022, Royal Society of Chemistry. p. 103-134. Figure 1
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Boniello, G., A. Stocco, C. Blanc, and M. Nobili. "Comment on “Brownian diffusion of a particle at an air/liquid interface: elastic (not viscous) response of the surface”." Physical Chemistry Chemical Physics 19, no. 33 (2017): 22592–93. http://dx.doi.org/10.1039/c7cp02970e.
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In a recent article Toro-Mendoza et al. considered an elastic response of an interface in order to explain the enhanced lateral drag of solid particles straddling fluid interfaces we recently measured.
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Strmcnik, Dusan, Dzevad K. Kozlica, Milena Martins, et al. "(Invited) Electrocatalysis at Modified Electrochemical Interfaces." ECS Meeting Abstracts MA2024-02, no. 61 (2024): 4116. https://doi.org/10.1149/ma2024-02614116mtgabs.
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Electrochemical energy storage and conversion technologies, which include fuel cells, electrolyzers, batteries, photoelectrochemical devices are at the forefront of the transition to a sustainable future. Although they have all been in use for more than half a century, they are far from reaching their full potential as defined by the laws of thermodynamics. Their performance rests almost entirely on the electrochemical interface - the boundary between the electronic conductor (electrode) and the ionic conductor (electrolyte). The desire of both phases to reduce the surface energy as well as the appearance of electrochemical potential across the interface can manifest itself as the formation of unique (near)surface atom arrangements (e.g. surface relaxation or reconstruction), as significant differences in electrode composition close to the surface (e.g. segregation profile), via substrate-adsorbate covalent and non-covalent interactions, via formation of a passive film as well as ordering of solvent and/or electrolyte molecules several nm away from the surface. This extremely complex and sensitive "interfacial bridge", is a consequence of inherent incompatibility of two materials, brought into contact, and is very hard to control. However, to control it means to control the energy efficiency, power density, durability and safety – the most important metrics of any energy conversion and storage device. In this presentation we will discuss, how the chemical nature of non-covalently and covalently [1,2] adsorbed species as well as thicker passive films and their morphology at the electrochemical interface affect the individual terms of the common rate equation [1], including the free energy of adsorbed intermediates and adsorbed spectators, mass transport, availability of active sites and electronic and ionic resistivity for common electrocatalytic reactions in acid and alkaline aqueous as well as in non-aqueous media on a plethora of metal electrodes (Pt, Ir, Au, Ni, Cu) as well as carbon. We will draw parallels between HER, OER, HOR and ORR in electrolyzers [1], fuel cells [2] and Li-ion batteries [3,4]. The interphase properties will be discussed through the lens of deviations of modified electrode properties from its intrinsic properties. Examples of artificially modified interfaces [5,6] will be given to demonstrate our ability to tailor their activity, stability and selectivity to our liking. [1] Strmcnik, D. Lopes, P.P., Genorio, B., et al. Design principles for hydrogen evolution reaction catalyst materials, Nano Energy, 29, 29-36 (2016) [2] Strmcnik, D., Uchimura, M., Wang, C. et al. Improving the hydrogen oxidation reaction rate by promotion of hydroxyl adsorption. Nature Chem 5, 300–306 (2013) [3] Strmcnik, D., Castelli, I.E., Connell, J.G. et al. Electrocatalytic transformation of HF impurity to H2 and LiF in lithium-ion batteries. Nat Catal 1, 255–262 (2018) [4] Martins, M., Haering, D., Connell, J.G., et al. Role of Catalytic Conversions of Ethylene Carbonate, Water, and HF in Forming the Solid-Electrolyte Interphase of Li-Ion BatteriesACS Catalysis 13, 9289-9301 (2023) [5] Zorko, M. Martins, P.F.B.D., Connell, J.G. et al. Improved Rate for the Oxygen Reduction Reaction in a Sulfuric Acid Electrolyte using a Pt(111) Surface Modified with Melamine, ACS Applied Materials & Interfaces 13, 3369-3376 (2021) [6] Strmcnik, D., Escudero-Escribano, M., Kodama, K. et al. Enhanced electrocatalysis of the oxygen reduction reaction based on patterning of platinum surfaces with cyanide. Nature Chem 2, 880–885 (2010)
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Borrel, Pascale. "Gestes de surface : Touching Reality de Thomas Hirschhorn et What Shall We Do Next? de Julien Prévieux." Interfaces, no. 40 (December 21, 2018): 55–65. http://dx.doi.org/10.4000/interfaces.601.
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Favaro, Marco. "(Invited) In Situ Photoelectron Spectroscopy Reveals the Chemical Nature of Semiconductor Surface States." ECS Meeting Abstracts MA2024-01, no. 35 (2024): 1981. http://dx.doi.org/10.1149/ma2024-01351981mtgabs.
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The accessible photovoltage of semiconducting photoabsorbers is typically 0.5-1 V below the theoretically achievable values predicted by the Shockley-Queisser limit [1]. Although the reason for this is still not well understood, surface and interface states within the photoabsorbers energy band gap may play a crucial role as they generally induce Fermi level pinning [2]. Within the PEC community, two key elements have been identified for the maximization of the photovoltage in photoelectrodes for water splitting: (i) the passivation of surface defects which is needed to avoid Fermi level pinning, and (ii) the increase of the minority carrier concentration at the interface to improve contact selectivity and optimize carrier extraction [3,4]. To understand the role of surface defects on Fermi level pinning, detailed information on the chemical nature and electronic properties of surface states is needed. Such information is usually obtained with UHV surface science techniques such as XPS, but the photoelectrode surface under UHV conditions has little, if any, relevance to the electrified surface when immersed in the electrolyte. Moreover, recent studies have shown that semiconductor surfaces are not static, but undergo extensive structural and chemical transformations during PEC device operation [5,6]. In this talk, we will show our recent development of state-of-the-art techniques to study the structure and dynamics of semiconductor/water interfaces under practically relevant conditions [7]. The chemical nature of the electronic states for selected semiconductors prepared at the Institute for Solar Fuels has been explored using synchrotron-based resonant, ambient pressure soft and hard X-ray photoelectron spectroscopy (AP-XPS and AP-HAXPES) [6,8-11], and with in situ/operando Raman and photoluminescence spectroscopy. In particular, we will show that it is possible to study photon-induced chemical changes at solid/liquid interfaces using AP-XPS and AP-HAXPES [6,8]. We will conclude this contribution by discussing about future perspectives and technical implementations for multimodal in situ/operando investigations of photoelectrocatalytic processes. [1] M.T. Mayer. Curr. Opin. Electrochem. 2017, 2, 104. [2] A. J. Bard et al. J. Am. Chem. Soc. 1980, 102, 3671. [3] A.G. Scheuermann et al., Nat. Mater. 2016, 15, 99. [4] M. Schleuning et al., Sustainable Energy Fuels, 2022, 6, 3701. [5] F.M. Toma et al., Nat. Commun. 2016, 7, 12012. [6] M. Favaro et al., J. Phys. Chem. B 2018, 122, 801. [7] M. Favaro et al., Surf. Sci. 2021, 713, 121903. [8] M. Favaro et al., J. Phys. D: Appl. Phys. 2021, 54, 164001. [9] M. Favaro et al., J. Phys. Chem. C 2019, 123, 8347. [10] W. Wang et al., J. Am. Chem. Soc. 2022, 144, 17173. [11] P. Schnell et al., Sol. RRL 2023, 2201104.
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Favaro, Marco. "(Invited) In Situ Photoelectron Spectroscopy Reveals the Chemical Nature of Semiconductor Surface States." ECS Meeting Abstracts MA2023-02, no. 48 (2023): 2434. http://dx.doi.org/10.1149/ma2023-02482434mtgabs.
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The accessible photovoltage of semiconducting photoabsorbers is typically 0.5-1 V below the theoretically achievable values predicted by the Shockley-Queisser limit [1]. Although the reason for this is still not well understood, surface and interface states within the photoabsorbers energy band gap may play a crucial role as they generally induce Fermi level pinning [2]. Within the PEC community, two key elements have been identified for the maximization of the photovoltage in photoelectrodes for water splitting: (i) the passivation of surface defects which is needed to avoid Fermi level pinning, and (ii) the increase of the minority carrier concentration at the interface to improve contact selectivity and optimize carrier extraction [3,4]. To understand the role of surface defects on Fermi level pinning, detailed information on the chemical nature and electronic properties of surface states is needed. Such information is usually obtained with UHV surface science techniques such as XPS, but the photoelectrode surface under UHV conditions has little, if any, relevance to the electrified surface when immersed in the electrolyte. Moreover, recent studies have shown that semiconductor surfaces are not static, but undergo extensive structural and chemical transformations during PEC device operation [5,6]. In this talk, we will show our recent development of state-of-the-art techniques to study the structure and dynamics of semiconductor/water interfaces under practically relevant conditions [7]. The chemical nature of the electronic states for selected semiconductors prepared at the Institute for Solar Fuels has been explored using synchrotron-based resonant, ambient pressure soft and hard X-ray photoelectron spectroscopy (AP-XPS and AP-HAXPES) [6,8-11], and with in situ/operando Raman and photoluminescence spectroscopy. In particular, we will show that it is possible to study photon-induced chemical changes at solid/liquid interfaces using AP-XPS and AP-HAXPES [6,8]. We will conclude this contribution by discussing about future perspectives and technical implementations for multimodal in situ/operando investigations of photoelectrocatalytic processes. [1] M.T. Mayer. Curr. Opin. Electrochem. 2017, 2, 104. [2] A. J. Bard et al. J. Am. Chem. Soc. 1980, 102, 3671. [3] A.G. Scheuermann et al., Nat. Mater. 2016, 15, 99. [4] M. Schleuning et al., Sustainable Energy Fuels, 2022, 6, 3701. [5] F.M. Toma et al., Nat. Commun. 2016, 7, 12012. [6] M. Favaro et al., J. Phys. Chem. B 2018, 122, 801. [7] M. Favaro et al., Surf. Sci. 2021, 713, 121903. [8] M. Favaro et al., J. Phys. D: Appl. Phys. 2021, 54, 164001. [9] M. Favaro et al., J. Phys. Chem. C 2019, 123, 8347. [10] W. Wang et al., J. Am. Chem. Soc. 2022, 144, 17173. [11] P. Schnell et al., Sol. RRL 2023, 2201104.
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Zdziennicka, Anna, Edyta Rekiel, Katarzyna Szymczyk, Wojciech Zdziennicki, and Bronisław Jańczuk. "Wetting Behaviour of Water, Ethanol, Rhamnolipid, and Triton X-165 Mixture in the Polymer–Solution Drop–Air System." Molecules 28, no. 15 (2023): 5858. http://dx.doi.org/10.3390/molecules28155858.
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Despite the fact that the wetting properties of multicomponent mixtures including the surface active compounds play a very important role in many practical applications, they are not sufficiently known. Thus, the wettability of polytetrafluoroethylene (PTFE) and poly (methyl methacrylate) (PMMA) by the water + ethanol (ET) solution of rhamnolipid (RL) with Triton X-165 (TX165) mixture was studied. The investigations involved measuring the advancing contact angles of this solution on PTFE and PMMA by varying the concentration of TX165 while maintaining a constant concentration of ET and RL. Additionally, a thermodynamic analysis was conducted to obtain the compositions and concentrations of the ET, RL, and TX165 mixtures at the different interfaces. The composition and concentration of the interface mixed layer were considered using two different approaches to the wetting process. From these considerations, it follows that, depending on the ET concentration, it is possible to form the TX165 + RL layer at the solid–water + ET mixed solvent, as well as the water + ET–air interfaces, but not at the solid–water and water–air ones. This conclusion is in accordance with the Gibbs standard free energy of adsorption of particular components of the studied mixture at the solution–air and solid–solution interfaces.
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Fraysse, Kilian, Lixu Huang, Hua Li, et al. "On the Parasitic Surface Adsorption of Pyrrolidinium and Phosphonium-Based Ionic Liquid Preventing Accurate Differential Capacitance Measurements." ECS Meeting Abstracts MA2024-02, no. 57 (2024): 3870. https://doi.org/10.1149/ma2024-02573870mtgabs.
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Ionic Liquids (ILs) have received a substantial interest from the scientific community over the past few decades1, in particular, because of their possible use as electrolytes for battery technology. This wide excitement stems from their known thermal stability and non-volatile nature2 (as opposed to more traditional organic carbonate-based electrolytes) which has led the study of IL to fall under the category of green chemistry3. In a similar fashion to aqueous-based electrolytes, whose bulk properties are fundamentally different from their properties near charged interfaces (giving rise to an Electrical Double Layer, EDL), ILs and IL-based electrolytes also exhibit a distinct interfacial structuring near charged surfaces consisting of alternating layers of cations and anions4 extending into the liquid over several nanometers5. This interfacial structuring (i.e., EDL) initially formed at the electrode/electrolyte interface defines the charge transfer mechanism6. It is also believed to play a critical role in the formation of the Solid Electrolyte Interphase (SEI)7,8. The latter, via its morphological, mechanical and chemical properties directly governs the performance of the battery9. Electrochemical Impedance Spectroscopy (EIS) is an attractive technique for the indirect study of the EDL at charged interfaces, via the so-called differential capacitance measurement. The latter giving an indication of the ionic density near the interface10. Differential capacitance measurements are, however, difficult to interpret and compare, because there is no real consensus as to how the measurement needs to be performed. To add to the difficulty, some ionic liquids are known to display a hysteresis process, inducing measurement variabilities. In this study, we propose to investigate the structure of the EDL of pure IL (trimethyl isobutyl phosphonium bis(fluorosulfonyl)imide, P111i4FSI and N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide, C3mpyrFSI) as well as IL-based electrolytes composed of 42mol% of NaFSI in C3mpyrFSI and/or P111i4FSI using both a differential capacitance and AFM approach. Using a well-established method for the measurement of the differential capacitance in IL and IL-based electrolytes, we show that all the studied systems display important hysteresis properties (in particular, the pyrrolidinium-based ones). Via a series of differential capacitance as well as AFM experiments, we further demonstrate that the hysteresis is a result of adsorption processes on the surface of the electrode. This parasitic adsorption leads inaccuracies in traditional differential capacitance measurements. We therefore propose an alternative method for the measurement of the differential capacitance which allows to minimize the impact of adsorption. This new understanding of differential capacitance measurements has important methodological implications. By providing guidelines for accurately probing the differential capacitance of ILs and IL-based electrolytes, in particular, pyrrolidinium and phosphonium-based ones via a single, reliable method, this report may well help pave the way to easier comparisons and interpretations. J.P. Hallett et al., Chem. Rev. 2011, 111, 3508-3576. S. Zhang et al., ACS Appl. Mater. Interfaces 2021, 13, 53904-53914. K. Paduszynski et al., J. Chem. Inf. Model. 2014, 54, 1311-1324. J.M. Black et al., ACS Appl. Mater. Interfaces 2017, 9, 40949-40958. R. Hayes et al., Chem. Rev. 2015, 115, 6357-6426. D. Rakov et al., Chem. Mater. 2021, 34, 165-177. Q. Wu et al., J. Am. Chem. Soc. 2023, 145, 2473-2484. D.S. Silvester et al., J. Phys. Chem. C 2021, 125, 13707-13720. Y. Zhou et al., Nat. Nanotechnol. 2020, 15, 224-230. J.M. Klein et al., Phys. Chem. Chem. Phys. 2019, 21, 3712-3720. Figure 1
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Howe, J. M. "Quantification of order in the liquid at a solid-liquid interface by high-resolution transmission electron microscopy (HRTEM)." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 114–15. http://dx.doi.org/10.1017/s0424820100163034.
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A number of different theoretical approaches have been used to model the atomic structure and properties of solid-liquid interfaces. Most calculations indicate that ordering occurs in the first several layers of the liquid, adjacent to the crystal surface. In contrast to the numerous theoretical investigations, there have been no direct experimental observations of the atomic structure of a solid-liquid interface for comparison. Saka et al. examined solid-liquid interfaces in In and In-Sb at lattice-fringe resolution in the TEM, but their data do not reveal information about the atomic structure of the liquid phase. The purpose of this study is to determine the atomic structure of a solid-liquid interface using a highly viscous supercooled liquid, i.e., a crystal-amorphous interface.
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Qu, Jianzhou, Zhou Yu, and Alexander Urban. "The Mechanism of Hydrogen Evolution Reaction at the Buried Interface of Silica-Coated Electrocatalysts." ECS Meeting Abstracts MA2023-01, no. 36 (2023): 2104. http://dx.doi.org/10.1149/ma2023-01362104mtgabs.
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Semipermeable oxide coatings can protect electrocatalysts in harsh environments without reducing the catalytic performance (Labrador, Esposito et al. ACS Catal. 8, 2018, 1767–1778), making them attractive for direct seawater electrolysis. We recently showed that the buried SiO2/Pt interface of silica-coated platinum electrocatalysts is environment-dependent and changes with the pH value of the electrolyte and the electrode potential (Qu and Urban, ACS Appl. Mater. Interfaces 12, 2020, 52125–52135). Here, we discuss the impact of silica membrane coatings on the hydrogen evolution reaction (HER) mechanism at the interface with different transition-metal surfaces. Stable configurations of the buried SiO2/TM interface at HER conditions were determined using density-functional theory (DFT) calculations. Computed Pourbaix diagrams for different transition-metal substrates show the pH and potential dependence of reaction intermediates and the hydrogen coverage on the metal surface. Our results indicate that the HER mechanism at the buried SiO2/catalyst interfaces may involve the silica membrane. Hence, besides the protective quality of silica membranes, this also points to the possibility of designing synergistic membrane-coated electrocatalysts that surpass the bare surfaces of earth-abundant transition metals in terms of catalytic performance (stability, activity, and/or selectivity).
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Huynh, Kenny, Michael Evan Liao, Xingxu Yan, et al. "Stability of Interface Morphology and Thermal Boundary Conductance of Direct Wafer Bonded GaN|Si Heterojunction Interfaces Annealed at Growth and Annealing Temperatures." ECS Meeting Abstracts MA2023-02, no. 33 (2023): 1605. http://dx.doi.org/10.1149/ma2023-02331605mtgabs.
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The properties of thin (~2 um) GaN templates on a silicon support substrate were studied to assess the stability of the direct wafer bonded GaN / Si interface. EVG® ComBond® equipment was used for bonding under high vacuum (~10-8 mtorr) at room temperature to remove unwanted native surface oxides [1,2]. For the bonded samples, the [1010] GaN edge was aligned parallel to the Si [110] edge. An X-ray diffraction reciprocal space map of the (004) Si and (0004) GaN revealed that there is a ~0.2° tilt between the GaN and Si layers and is simply due to the relative miscut between the two wafers. The treatment of the surfaces prior to bonding produces an amorphous region at the bonded interface that has been seen in many other bonded systems [3-5]. In the as-bonded sample, high resolution scanning transmission electron microscopy revealed a ~2 nm amorphous region on the Si side of the bonded interface, as confirmed by energy dispersive x-ray spectroscopy (EDX). Subsequent annealing was performed in an effort to recrystallize the amorphous interface. Previous work has shown that recrystallization between Si|Si wafer bonded samples occurred when annealed at 450 °C for 12 hours [3]. However, in the GaN|Si system, we found that the amorphous interface did not recrystallize when annealed under those conditions. Annealing at temperatures up to 450 °C and 120 hours showed only initial stages of interdiffusion and a stable interface. However, after annealing at 700 °C for 24 hours, high resolution EDX revealed the formation of amorphous SiN as well as the diffusion of gallium into silicon. Preliminary thermal results show that the thermal boundary conductance (TBC) of the as bonded sample is ~140 MW/(m2K). The TBC results of wafer bonded GaN|Si reported here is higher than previously reported TBC values of epitaxially grown interfaces such as GaN on Si [6], GaN on SiC [7], and GaN on diamond [8]. The TBC for the annealed interface is degraded by a factor of two compared to the as-bonded interface for the sample that was annealed at 700 °C for 24 hours. These results demonstrate that high TBC can be achieved through wafer bonding of GaN with materials such as silicon and that such interfaces are stable even up to device operation up to 300 °C. However, chemically rough interfaces formed due to high temperature annealing are detrimental to thermal transport across these interfaces. V. Dragoi, et al., ECS Trans., 86(5), 23 (2018) C. Flötgen, et al., ECS Trans., 64(5), 103 (2014) M.E. Liao, et al., ECS Trans., 86(5), 55 (2018) Y. Xu, et al., Ceramics International, 45, 6552 (2019) F. Mu, et al., Appl. Surf. Sci., 416, 1007 (2017) L. Yates, et al., ASME InterPACK (2015) J. Cho, et al., Phys. Rev. B, 89, 115301 (2014) H. Sun, et al., APL, 106(11), 111906 (2015) Figure 1
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Degoulange, Damien, Raj Pandya, Michael Deschamps, et al. "Micrometer Thick Interfaces in Aqueous Biphasic Systems for Electrochemical Devices." ECS Meeting Abstracts MA2023-01, no. 1 (2023): 460. http://dx.doi.org/10.1149/ma2023-011460mtgabs.
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Aqueous biphasic systems (ABSs) consist of two immiscible phases composed of only one solvent (water) with the phase separation driven by solutes such as polymers, ionic liquids and salts. Such two-phase systems have proved highly relevant in recent years for applications in electrochemical devices. Indeed, highly concentrated solutions of LiTFSI, so called “Water-in-salt” battery electrolyte, were recently found to form an ABS with LiX (with X=Cl, Br, I) aqueous solutions (Dubouis et al., ACS Cent. Sci. 2019, 5, 640-643 and Dubouis et al., J. Phys. Chem. B 2021, 125, 5365-5372). These LiTFSI-LiX ABSs enable the intercalation at high potential of halides such as Cl- or Br- into graphite, in lieu of the oxidation of water or the evolution of halogenated gas, thus enabling the assembly of efficient dual-ion batteries (Yang et al., Nature 2019, 569, 245-250). Similarly, ABS have been proposed to prevent problematic crosstalk mechanisms as observed in Li-ion/sulfur batteries (Yang et al., Proc. Natl. Acad. Sci. 2017, 114, 6197-6202) or to be used to design membraneless redox flow batteries (Navalpotro et al., Adv. Sci. 2018, 5, 1800576). However for ABS to be widely implemented in electrochemical devices, the ion transfer at liquid/liquid interface is key in obtaining good (dis)charge rate and preventing self-discharge. Thus, it is crucial to first understand the structure and chemistry of these aqueous interfaces. We studied the LiTFSI-LiCl ABS first with Fourier transform infrared spectroscopy (FT-IR) and surface tension measurement to assess ion partition and surface tension respectively. Both ion partition and surface tension are found increasing as function of increasing concentration. Such trend of the surface tension is typical of a negative adsorption of ions at the liquid/liquid interface. Using high spatial resolution Raman imaging, we were able to confirm a negative adsorption of ions by assessing the ion concentration profiles at the interface between the two aqueous phases. Indeed, we found concentration profiles of water and ions to be sigmoidal which is characteristic of a negative adsorption. Strikingly, the length of the negative adsorption is ranging from 11 to 2 μm with increasing concentrations and the Raman spectra of water and TFSI anion are continuously changing along the interface from an environment with weak hydrogen bounding network and with anion aggregate to an environment similar to diluted solutions. Moreover, when changing the cation from Li+ to H+, the temperature dependence of the phase diagram is inversed, as we could show by variable temperature nuclear magnetic resonance (VT-NMR) and micro-calorimetry, but the interface is still few microns thick. Thus, we revealed a continuous change in the chemical environment between two aqueous phases at the micrometer scale, which contrast drastically with the interface between two immiscible electrolyte solutions (ITIES) such as oil-water systems where molecularly sharp, nanometer interface are found. Such difference raise question about the impact of the thickness and the chemical composition of the interface on the dynamics of ion and electron transfer at the interface, that we are studying by electrochemical measurements. Furthermore, this work paves the way to compare liquid/liquid and solid/liquid interfaces in order to understand how ion solvation affects the interfacial ion transfer and thus enable a better engineering of the electrolyte and ABSs for better electrochemical devices.
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Grunder, Yvonne, Christopher A. Lucas, Yves Joly, and Yvonne Soldo-Olivier. "(Invited) In Situ x-Ray Diffraction Studies of the Atomic Structure and Charge Distribution at the Electrochemical Interface." ECS Meeting Abstracts MA2024-01, no. 46 (2024): 2603. http://dx.doi.org/10.1149/ma2024-01462603mtgabs.
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The presence of specifically adsorbed anions can significantly affect the electrochemical reactivity of a metal electrode which is of major interest for galvanic deposition, etching, corrosion and electrocatalysis. In-situ surface x-ray diffraction has enabled an atomic/molecular-level understanding of the interface under reactive conditions, including its potential and time dependence, to be developed. While information about the atomic structure of the electrode surface in electrochemical in-situ cells has been widely investigated, insight into the charge distribution and the structure of the electrolyte at the interface is still lacking. Advances in these directions offer possibilities in elucidating atomic scale models of the electrochemical interface and thus will help to establish structure-stability-reactivity relationships. A fundamental understanding of the nature of the charge transfer, especially the influence of the applied potential and the screening by the electrolyte, is a major goal in electrochemistry to better understand electrochemical processes and charge transfer during adsorption and deposition. [1] Thus, combining x-ray spectroscopy and x-ray diffraction to gain site specific information about the charge distribution at buried interfaces is a promising tool. [2,3] Examples of how the use of surface x-ray scattering techniques can help to characterize electrochemical interfaces in-situ in order to link, structure, reactivity and stability will be presented. [4-5] Advances in these directions offer possibilities in elucidating atomic scale models of the electrochemical interface and thus will help to establish structure-stability-reactivity relationships and to understand growth kinetics and electrochemical phase formation. References: [1] Y. Gründer and C. A. Lucas, Nano Energy 29, 378 (2016). [2] Y. Gründer, P. Thompson, A. Brownrigg, M. Darlington, and C. A. Lucas, Journal of Physical Chemistry C 116, 6283 (2012). [3] Y. Joly et al., Journal of Chemical Theory and Computation 14, 973 (2018). [4] Y. Grunder et al., Charge Reorganization at the Adsorbate Covered Electrode Surface Probed through in Situ Resonant X-ray Diffraction Combined with ab Initio Modeling; Phys. Chem. C 2022, 126, 9, 4612–4619 [5] Yvonne Soldo-Olivier et al., Unraveling the Charge Distribution at the Metal-Electrolyte Interface Coupling in Situ Surface Resonant X-Ray Diffraction with Ab Initio Calculations, ACS Catal. 2022, 12, 4, 2375–2380
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Vivian, Robert. "Interfaces glace-roche et érosion sous-glaciaire." Revue de géographie alpine 76, no. 2 (1988): 207–18. http://dx.doi.org/10.3406/rga.1988.2707.
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Magnussen, Olaf M. "Operando Studies of Electrochemical Interfaces By High-Energy Surface x-Ray Scattering." ECS Meeting Abstracts MA2023-02, no. 55 (2023): 2679. http://dx.doi.org/10.1149/ma2023-02552679mtgabs.
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Knowledge on the atomic-scale structure of the electrode-electrolyte interface is of key importance for understanding electrochemical reactivity. This includes the structure of the atomic layers at the electrode surface, the arrangement of chemisorbed species on the surface, and the near-surface structure of the adjacent electrolyte, i.e., the electrochemical double layer. Surface X-ray scattering (SXRD) methods can provide such information and have been used for decades to obtain important insights into various structural aspects of electrochemical systems. However, conventional SXRD is limited by the considerable time required for a full characterization of the three-dimensional interface as well as in terms of the structural detail that can be reliably extracted from the diffraction data by structural models. This is related to the slow sequential data acquisition necessary for such measurements. We here describe in situ and operando studies of electrochemical interface structure by High Energy Surface X-ray Diffraction (HESXRD), where the interface structure is probed by hard X-rays with high photon energy (in this work 70 keV). This method has been originally developed for studies of catalyst surfaces in the gas phase [1], but is starting to be applied increasingly to electrochemical systems. In combination with the highly brilliant beams provided by emerging hard X-ray 4th generation synchrotron, HESXRD allows to obtain very large datasets in short time. From these the interface structure can be determined with unprecedented detail by a quantitative analysis of the measured crystal truncation rods (CTRs). Furthermore, measurement of restricted datasets is possible with even high time resolution down to the second or sub-second regime, which is ideal for monitoring fast kinetic changes in operando. We illustrate the capabilities of HESXRD by studies of platinum surface oxidation and magnetite single crystal electrodes under oxygen evolution conditions. For the case of platinum we present data on Pt(111), Pt(100), and Pt(110) in 0.1 M HClO4 that reveal distinct differences in the structure and formation mechanisms of the Pt surface oxide [2]. Because of these differences, the irreversible surface restructuring and Pt dissolution during oxidation/reduction cycles depends strongly on the crystallographic orientation. In addition, we demonstrate for Pt(111) that the extraction of Pt atoms out of the electrode surface in the initial stages of oxidation is not directly coupled to the charge transfer associated with the formation of adsorbed oxygen species [3]. Studies on magnetite focus on Fe3O4(100) in 0.1 M NaOH, where previous SXRD studies showed that the (√2x√2)R45° reconstructed surface formed under UHV conditions can be maintained [4]. HESXRD allowed to obtain extended CTR datasets, which provide deeper insights into the structure of this oxide model electrocatalyst. [1] J. Gustafson et al., Science 343, 758 (2014) [2] T. Fuchs et al., Nature Catalysis 3, 754 (2020) [3] T. Fuchs et al., J. Phys. Chem. Lett. 14, 3589 (2023), https://doi.org/10.1021/acs.jpclett.3c00520 [4] D. Grumelli et al., Ang. Chem. Int. Ed. 59, 49 (2020)
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Hafidi, K., M. Azizan, Y. Ijdiyaou, and E. L. Ameziane. "Ètude des interfaces SiO2/TiO2 et TiO2/SiO2 dans la structure SiO2/TiO2/SiO2/c-Si préparée par pulvérisation cathodique radio fréquence." Canadian Journal of Physics 85, no. 7 (2007): 763–76. http://dx.doi.org/10.1139/p07-053.
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The atomic structure of the TiO2/SiO2 and SiO2/TiO2 interfaces has been investigated in SiO2/TiO2/SiO2 multilayers deposited by radio frequency reactive sputtering without breaking the vacuum on the crystalline substrate cooled by water. The characterizations of these interfaces have been performed using three complementary techniques sensitive to surface and interface state: X-ray photoelectron spectroscopy (XPS), grazing incidence X-ray diffraction (GIXD), and specular X-ray reflectometry (GIXR). The concentration profiles and Si2p and O1s core level chemical displacements show that TiO2/SiO2 and SiO2/TiO2 interfaces are very diffuse. The reflectometry measurements confirm this character and indicate that the silicon, titanium, and oxygen atomic concentrations vary gradually at the interfaces. The grazing incidence X-ray spectra indicates that the interfacial layers are not well crystallized and are formed by SiO2-TiO2, TiO, Ti2O3, Ti3O5, Ti5Si3, Ti5Si4, TiSi, and TiSi2 components.
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Grunder, Yvonne. "Perspectives and Impact of in-Situ X-Ray Techniques for Electrodeposition." ECS Meeting Abstracts MA2022-02, no. 24 (2022): 1003. http://dx.doi.org/10.1149/ma2022-02241003mtgabs.
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In-situ surface x-ray diffraction has enabled an atomic/molecular-level understanding of the electrochemical interface, including its potential and time dependence, to be developed. [1] Specifically, for electrodeposition the influence of additives and adsorbates onto growth and nucleation behaviour could be established. Halogens on metal surfaces are prototypic adsorbate systems but the adsorption of halide ions especially on copper is also of major importance for on-chip metallization in ULSI microchip production. Halide ions on Cu surfaces form an inhibiting adsorbate layer with polyethylene glycol (PEG). Even though the influence of the additives combination on the shape evolution of the Cu deposit was subject of numerous studies, their precise role during the elementary steps of the deposition with regards to altering the charge distribution and dipole moment at the interface is largely not understood. [1] While information about the atomic structure of the electrode surface in electrochemical in-situ cells has been widely investigated, insight into the charge distribution and the structure of the electrolyte at the interface is still lacking. Combining x-ray spectroscopy and x-ray diffraction to gain site-specific information about the charge distribution at buried interfaces is a promising tool. [2,3,4] Studies on the metal-halide interface and how the use of surface x-ray scattering techniques can help to characterise electrochemical interfaces in-situ in order to link, structure and stability and morphology changes will be presented. [1, 4] Advances in these directions offer possibilities in elucidating atomic scale models of the electrochemical interface and thus will help to establish structure-stability-reactivity relationships which will help to understand growth kinetics and nucleation behaviour. References: [1] In-Situ Surface X-ray Diffraction Studies of Copper Electrodes: Atomic-Scale Interface Structure and Growth Behavior. Gruender, Y., Stettner, J., & Magnussen, O. M. (2018). Journal of the Electrochemical Society; 166(1), D3049-D3057. doi:10.1149/2.0071901jes [2] Probing the charge distribution at the electrochemical interface; Y. Gründer and C. A. Lucas, Physical Chemistry Chemical Physics, 2017, 19, 8416 [3] Simulation of Surface Resonant X-ray Diffraction; Y. Joly et al., J. Chem. Theory Comput,. 2018, 14, 973−980 [4] Charge Reorganization at the Adsorbate Covered Electrode Surface Probed through in Situ Resonant X-ray Diffraction Combined with ab Initio Modeling;Y. Grunder, C. A. Lucas, P. B. J. Thompson, Y. Joly, Y. Soldo-OlivierJ. Phys. Chem. C 2022, 126, 9, 4612–4619
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Macak, Jan M., Raul Zazpe, Hanna Sopha, Jhonatan Rodriguez Pereira, and Bilal Bawab. "Atomic Layer Deposition on Anodic TiO2 Nanotubes for Electrochemical Applications." ECS Meeting Abstracts MA2024-02, no. 16 (2024): 1663. https://doi.org/10.1149/ma2024-02161663mtgabs.
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One-dimensional nanomaterials – materials with one dimension outside the nanoscale, further noted as 1D NMs – represent a class of very important nanomaterials with continuously increasing importance. Due to their intrinsic features, unique properties and diversity of functionalities, they count among the most widely studied materials nowadays. While considerable research efforts have been spent to synthesize various 1D NMs (e.g. nanopores, nanotubes or nanofibers), limited efforts have been devoted to surface modification and property tailoring of these materials. However, it is their surface that comes into direct contact with various media (air, gases, liquids, solids) and influences the reactivity, stability and biocompatibility of these materials. The surface and aspect ratio (defined as their diameter to length ratio) influence the performance of these materials in various applications. Considering these facts, it is more relevant to tailor the surface of these materials and to be able to influence their properties and reactivity at the nanoscale, rather than to deal with tailoring their own bulk material composition. The focus of this presentation is on the modification of anodic TiO2 nanotubes by coatings achieved by Atomic Layer Deposition (ALD). From all available techniques, ALD is the only capable of really uniform and homogenous coating of these 1D nanomaterials, in particular those of very high-aspect ratio. Experimental details and some very recent application examples in electrocatalysis, photocatalysis, sensors, batteries, etc. [1-10] and structural characterizations of these modified materials will be discussed. Sopha et al (2017), Appl. Mater. Today, 9, 104. Sopha et al. (2018), Electrochem. Commun.,97, 91. Ng et al. (2017), Adv. Mater. Interfaces, 1701146. Dvorak et al. (2019), Appl. Mater. Today, 14, 1. Sopha et al. (2019), FlatChem 17, 100130. Motola et al. (2019), Nanoscale 11, 23126. Ng et al. (2020), ACS Appl. Mater. Interfaces, 12, 33386. Bawab et al. (2022) Electrochimica Acta 429, 141044. Wiltshire et al. (2023) ACS Appl. Mater. Interfaces 15, 18379 Galstyan, J. M. Macak, T. Djenizian, (2022), Appl. Mater. Today, 29, 101613
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Deka, Nipon, and Rik Mom. "Probing of Near-Surface Cations during the Oxygen Evolution Reaction (OER) Using Operando XAS." ECS Meeting Abstracts MA2023-02, no. 55 (2023): 2669. http://dx.doi.org/10.1149/ma2023-02552669mtgabs.
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Electrified solid-liquid interfaces are ubiquitous in technologies ranging from colloidal science to electrochemistry. Hence, an atomic-level characterization of the electrode-electrolyte interface is crucial for total control and optimization of the processes involved. While the electrode side of the interface has been quite extensively studied, the electrolyte side is comparatively poorly understood1. Specifically probing the near-surface electrolyte species during an electrochemical reaction is a major technical challenge in the field of catalysis and surface chemistry. We have developed an interface-sensitive X-ray absorption spectroscopy (XAS) approach which allows us to directly probe the near-surface cations and anions of the electrolyte under applied potentials. In this approach, we employ a mesoporous electrocatalyst film coated on a 𝑆𝑖𝑁𝑥 X-ray window. These mesoporous films exhibit an extremely high electrode-electrolyte interface area, enabling us to specifically probe the behaviour of interfacial ions via their K-edge spectra. Using this approach, we have recently investigated the interaction of Na+ cations with IrOx during the oxygen evolution reaction (OER), which is a bottleneck in major electrochemical processes like green hydrogen production and CO2 reduction. The cations and anions of the electrolyte reportedly influence the OER activity of electrodes during OER2,3. We used operando Na K-edge XAS to directly probe the concentration and coordination environment of the near-surface Na+ cations. Simultaneously, operando O K-edge XAS monitored the interfacial water structure and the evolution of catalyst’s surface structure. Contrary to expectations, we discovered that the positively charged Na+ ions are drawn to the IrOx surface by more positive potentials only at alkaline pH. This finding cannot be explained by any of the electrolyte theories4 put up thus far, emphasizing the necessity of a detailed investigation of interfacial electrolyte structures. References: Arminio-Ravelo et al. ChemPhysChem 20, (2019). Tymoczko et al. Catal. Today 244, (2015). Ganassin et al. Phys. Chem. Chem. Phys. 17, (2015). Waegele et al. J. Chem. Phys. 151, (2019). Figure 1
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Mohseni Armaki, Seyedamirhossein, Majid Ahmadi, Arjan Mol, and Peyman Taheri. "In Situ Probing Electrified Interfacial Molecular Anion Structures at Atomically Flat Gold Electrode." ECS Meeting Abstracts MA2024-02, no. 61 (2024): 4130. https://doi.org/10.1149/ma2024-02614130mtgabs.
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Electrochemical interfaces—buried between electrodes and electrolytes—are notoriously difficult to probe, and enormous efforts, both experimentally and computationally, have been devoted to this endeavour. Although some progress has been made, the microscopic structures of electrochemical interfaces remain elusive and a great challenge in physical sciences.[1] Answering this question is not only of fundamental interest but also of technological importance in a broad range of research areas in science and technology, to name a few, energy storage in supercapacitors, electrocatalysis of relevance to energy and environmental applications, self-assembly of colloidal particles, ion transport across biological membranes, and mineralization processes in earth science. Despite its significance, molecular-level understanding of Electrified Double Layer (EDL) is largely missing, owing to its complexity and small scale making it difficult to probe. Because of the advent of advanced experimental (e.g., synchrotron-based techniques and Raman spectroscopy) and computational methods [e.g., ab intio molecular dynamics (AIMD)], it is not until recently that the microscopic structures of EDL have started to be unveiled. [2,3] In this study, we employ in-situ Shell Isolated Nanoparticle Enhance Raman spectroscopy (SHINERS) to investigate the structures of electric double layers at electrochemical interfaces. Specifically, we focus on understanding the arrangement and surface interaction of anions on electrified gold single-crystal electrode surfaces under varying bias potentials. We discuss how these ions orient themselves and interact with the electrode surface, and how these interactions influence local permittivity and ion-surface attraction, ultimately impacting the structure and behavior of the EDL and electrochemical processes. [1] Le et al., Sci. Adv. 2020; 6 [2] Li et al.,Nature Materials, 2020; 18 [3] Wang et al., ,Nature, 2021;600
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Chau, Allison L., Jonah Rosas, George D. Degen, et al. "Correction: Aqueous surface gels as low friction interfaces to mitigate implant-associated inflammation." Journal of Materials Chemistry B 8, no. 42 (2020): 9813. http://dx.doi.org/10.1039/d0tb90177f.
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Baeumer, Christoph. "(Invited) Electrochemistry Happens at the Interface." ECS Meeting Abstracts MA2023-02, no. 67 (2023): 3208. http://dx.doi.org/10.1149/ma2023-02673208mtgabs.
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Earth-abundant, active, selective and stable electrocatalysts are the cornerstone in our transition to defossilisation of the chemical industry, sector coupling, and sustainable energy. The catalyst surface is known to transform at the interface to the electrolyte, especially under operation conditions. Only the properties of the transformed interface coupled to the underlying layer gives rise to observed metrics like activity and stability. This complicates predictive electrocatalyst materials design – a challenge which can only be tackled by collaborative and interdisciplinary efforts, at the Interface between Chemistry, Physics, Materials Science, and Engineering. I believe this presents one of the main tasks for the young electrochemistry researchers in Europe and around the world, especially since the same challenges also arise in related technologies like Li-ion batteries. In my talk I will discuss how the old wisdom from semiconductor research “the Interface is the device” can be translated into the current challenge “Electrochemistry happens at the Interface”. We need new approaches in designing and studying these electrochemical interfaces for fundamental insights that may in a next step yield better performance in future applications. The talk will be split in two parts. Firstly, I will introduce how single crystalline surfaces can be obtained using epitaxial thin films, and discuss how these can be used to derive atomic-level structure-property relations by synergetic experimental and theoretical investigation. Such films can be fabricated with unit-cell or even atomic-layer precision and enable direct comparison to single facets typically investigated in density functional theory. Secondly, I will discuss opportunities and challenges in surface-sensitive operando characterization in a liquid medium.1 Information from the outermost surface of a catalyst can be obtained through a standing-wave approach2,3 or extraction of a surface-only signal from careful thickness-dependent studies.4 In my ERC project “Interfaces at work”, we are also developing interface-sensitive, laboratory-based operando X-ray photoelectron spectroscopy approaches based on the new XPS user facility at the University of Twente. Throughout the talk, I will refer to examples from LaNiO3 thin films, which are atomically flat both before and after application as electrocatalysts for the OER during water electrolysis. We selectively tuned the surface cationic composition in epitaxial growth. The Ni-termination is approximately twice as active for the OER as the La-termination.2 Our ex situ and operando characterization confirmed that the surface transformation pathways – and therefore the electrochemical functionality – depend on a single atomic layer at the surface. A second example will be the introduction of multi-cation compositions in so-called high entropy perovskite oxides (HEO), which can maximize the catalytic activity. The HEO LaCr0.2Mn0.2Fe0.2Co0.2Ni0.2O3-δ outperforms all of its parent compounds (single TM-site element in the LaTMO3 perovskite) by orders of magnitude.5 X-ray photoemission studies reveal a synergistic effect of simultaneous oxidation and reduction of different transition metal cations during adsorption of reaction intermediates. Rao, R. R., van den Bosch, I. C. G. & Baeumer, C. Operando X-ray characterization of interfacial charge transfer and structural rearrangements. in Reference Module in Chemistry, Molecular Sciences and Chemical Engineering 1–24 (Elsevier, 2023). doi:10.1016/B978-0-323-85669-0.00068-4. Baeumer, C. et al. Tuning electrochemically driven surface transformation in atomically flat LaNiO3 thin films for enhanced water electrolysis. Nat Mater 20, 674–682 (2021). Martins, H. P. et al. Near total reflection x-ray photoelectron spectroscopy: quantifying chemistry at solid/liquid and solid/solid interfaces. J Phys D Appl Phys 54, 464002 (2021). Baeumer, C. Operando characterization of interfacial charge transfer processes. J Appl Phys 129, 170901 (2021). Kante, M. V et al. A High-Entropy Oxide as High-Activity Electrocatalyst for Water Oxidation. ACS Nano (2023) doi:10.1021/acsnano.2c08096. Figure 1
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Pimponi, D., M. Chinappi, P. Gualtieri, and C. M. Casciola. "Hydrodynamics of flagellated microswimmers near free-slip interfaces." Journal of Fluid Mechanics 789 (January 22, 2016): 514–33. http://dx.doi.org/10.1017/jfm.2015.738.
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The hydrodynamics of a flagellated micro-organism is investigated when swimming close to a planar free-slip surface by means of numerical solutions of the Stokes equations obtained via a boundary element method. Depending on the initial conditions, the swimmer can either escape from the free-slip surface or collide with the boundary. Interestingly, the micro-organism does not exhibit a stable orbit. Independently of escape or attraction to the interface, close to a free-slip surface, the swimmer follows a counter-clockwise trajectory, in agreement with experimental findings (Di Leonardo et al., Phys. Rev. Lett., vol. 106 (3), 2011, 038101). The hydrodynamics is indeed modified by the free surface. In fact, when the same swimmer moves close to a no-slip wall, a set of initial conditions exists which result in stable orbits. Moreover, when moving close to a free-slip or a no-slip boundary, the swimmer assumes a different orientation with respect to its trajectory. Taken together, these results contribute to shed light on the hydrodynamical behaviour of micro-organisms close to liquid–air interfaces which are relevant for the formation of interfacial biofilms of aerobic bacteria.
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Makiura, Rie. "(Invited) air/Liquid Interfacial Formation Process of Electrically Conductive Metal-Organic Framework Nanosheets." ECS Meeting Abstracts MA2024-02, no. 37 (2024): 2551. https://doi.org/10.1149/ma2024-02372551mtgabs.
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Development of rational methods for creating ordered two-dimensional (2D) structures with nanometer scale precision is one of the central issues in the nanoscience and nanotechnology fields because of their intrinsic physical-chemical properties which are seen in those of their equivalent bulk state. Inclusion of highly regulated nanopores into the nanosheet structure will further open the possible applications such as nanosieves, molecular/ion storage and sensor devices as well as introducing guest molecules into the nanopores tune variedly the sheet properties (electric conduction, nanoheterojunction). Utilizing molecular building units are suitable for creating such porous nanosheets because of rich variety of design and facile modification of size and shape. Here, I present a facile bottom-up synthesis of molecular nanosheets with both positional and size regulated nanopores utilizing air/liquid interfaces[1-5]. By applying liquid interfaces, growth direction of the object can be well controlled with utilizing self-assembly feature of the molecules under mild conditions. We have succeeded to tune finely the nanosheet structures by rational modification of molecular building units . The highly crystalline structure remains after transferring a solid substrate from the liquid surface as well as without any supports. Notably, such highly oriented porous crystalline structure is obtained specifically by applying bottom up synthesis at air/liquid interfaces, not by other techniques. I also present detailed insights into the formation process of electrically conductive MOF nanosheets composed of 2,3,6,7,10,11-hexaiminotriphenylene (HITP) and Ni(II) ions (HITP-Ni-NS) at the air/liquid interface [6-8]. The morphological and structural features of HITP-Ni-NS strongly depend on the standing time—the time without any external actions involved, but leaving the interface undisturbed after setting the ligand solution onto the metal-ion solution. We find that the fundamental features of HITP-Ni-NS are determined by the standing time with conductivity sensitively influenced by such pre-determined HITP-Ni-NS characteristics. These findings will lead towards the establishment of a rational strategy for creating MOF nanosheets at the air/liquid interface with desired properties, thereby accelerating their use in diverse potential applications. 1. R. Makiura et al. Nature Mater. 9, 565 (2010). 2. S. Motoyama, R. Makiura, O. Sakata, H. Kitagawa, J. Am. Chem. Soc. 133, 5640 (2011). 3. R. Makiura, O. Konovalov, Sci. Rep. 3, 2506 (2013). 4. R. Makiura et al. ACS Nano, 11, 10875–10882 (2017). 5. R. Makiura et al, Coord. Chem. Rev. 469, 214650 (2022). 6. R. Makiura et al, ACS Appl. Mater. Interfaces, 13, 54570 (2021). 7. R. Makiura et al, J. Colloid Interface Sci. 651, 769 (2023). 8. R. Makiura et al, Langmuir. 39, 8952 (2023). Figure 1
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Listorti, Andrea, Sara Covella, Alberto Perrotta, et al. "(Invited) Plasma Processes on Metal Halide Perovskite Interfaces for Photovoltaic Applications." ECS Meeting Abstracts MA2023-01, no. 14 (2023): 1342. http://dx.doi.org/10.1149/ma2023-01141342mtgabs.
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Metal Halide Perovskite (MHP) semiconductors are currently standing out for their exceptional optoelectronic properties and, particularly, for their exploitation in photovoltaics. Their structure can be described by the formula , where A is usually an organic cation, such as methylammonium (MA) or formamidinium (FA), B is a metal cation and X is a halogen anion, typically I or Br. The exceptional properties of MHPs derive by their hybrid organic-inorganic nature, which also allows for low-cost fabrication processing. The raise of perovskite photovoltaics 1 followed progresses on three main research fronts: i) material deposition optimization, ii) material compositional tuning and iii) device interface engineering. The interfaces play a fundamental role in the device function affecting charge extraction, recombination processes and material/device overall stability. Therefore, to further improve the performances of these devices, many surface processes have been applied to solar cells interfaces, most of which include a solution-based methodology 2. The aim of these treatments is not only to improve solar cells efficiency in terms of carrier concentration and transport properties, but also to improve the device stability under working conditions, which is one of the main issues of these materials. Among the different surface treatments exploitable, the use of plasma represents a solvent-free and non-invasive promising strategy to boost MHP solar cells performances. Plasma-deposited coatings on perovskite, as fluorocarbon polymers, have shown to improve material resistance to humidity and photoluminescence properties 3. We have explored the effect of low-pressure plasmas fed with different gases, namely Ar, , and , on Metylammonium Lead Iodide surface4. An interesting improvement of perovskite photoluminescence and solar cell efficiency was observed for Ar and plasma treatments, ascribable both to the removal of organic components, proven to be beneficial to device performances 5, and to other chemical and morphological modifications depending on the gas used. Starting from these results, new plasma surface treatments, plasma-assisted deposition and encapsulation processes will be object of study of future research, to achieve a more complete understanding of the interfacial defects and charge carrier dynamics and to further minimize performance losses and instability issues. References NREL Best Research-Cell Efficiency Chart. https://www.nrel.gov/pv/cell-efficiency.html Han TH, Tan S, Xue J, Meng L, Lee JW, Yang Y. Interface and Defect Engineering for Metal Halide Perovskite Optoelectronic Devices. Advanced Materials. 2019;31(47). doi:10.1002/adma.201803515 Armenise V, Colella S, Milella A, Palumbo F, Fracassi F, Listorti A. Plasma-Deposited Fluorocarbon Coatings on Methylammonium Lead Iodide Perovskite Films. Energies (Basel). 2022;15(13):4512. doi:10.3390/en15134512 Andrea Listorti, Sara Covella, Alberto Perrotta, et al. A study on plasma-assisted modifications of Methylammonium Lead Iodide Perovskite surfaces for photovoltaic applications. Xiao X, Bao C, Fang Y, et al. Argon Plasma Treatment to Tune Perovskite Surface Composition for High Efficiency Solar Cells and Fast Photodetectors. Advanced Materials. 2018;30(9):1-7. doi:10.1002/adma.201705176 Figure 1
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Temperton, Robert, Mattia Scardamaglia, Suyun Zhu, and Andrey Shavorskiy. "Soft X-Ray Operando Characterization of Electrochemical Interfaces." ECS Meeting Abstracts MA2023-02, no. 55 (2023): 2667. http://dx.doi.org/10.1149/ma2023-02552667mtgabs.
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HIPPIE is a high-flux, high-resolution soft x-ray beamline at MAX IV Laboratory (Sweden) with a new dedicated experimental setup for operando studies of electrochemical interfaces.[1] Such experiments utilize the dip-and-pull method to form a thin liquid meniscus on the surface of the working electrode in a three-electrode cell with a liquid electrolyte solution. Both the liquid film itself and the electrode-electrolyte interface can then be probed using X-ray photoelectron spectroscopy (PES) whilst maintaining full electrochemical control. The technique can be used to probe oxidation state changes, chemical shifts, electronic structure and electrochemical potentials in-situ. In this talk we will discuss status of spectroelectrochemical PES using soft X-rays, discussing the merits of the various different approaches to cell design. We will present three case studies on the topics of molecular redox reactions, battery interfaces and metal corrosion, all of which can be studied using dip-and-pull.[2-4] We will primarily aim to provide an introduction to the dip-and-pull method for those interested in this genre of advanced operando characterization. We will additionally outline the experimental realities and challenges that any potential new user of the dip-and-pull method should be aware of before applying for beamtime to conduct an experiment. The three case studies were all measured at HIPPIE, where the beamline operates in the 250-2000 eV range, providing access to the L absorption edges of many transition metals and the K edges of light elements. The dip-and-pull PES experiments are realized with an ambient-pressure hemispherical electron analyzer allowing measurements in vapor pressures up to 25 mbar. Electrochemical cells can therefore use aqueous electrolyte solutions as well as some organic solvents, including many of those common in batteries. An argon/nitrogen atmosphere glove box can be attached to the measurement chamber such that air sensitive materials can be studied. Typically foils or thin films are used for the working electrode. This apparatus therefore provides one of the most flexible platforms for electrochemical studies using soft-X-ray spectroscopy. References: [1] S. Zhu et al., HIPPIE: a new platform for ambient-pressure X-ray photoelectron spectroscopy at the MAX IV Laboratory, Journal of synchrotron radiation, 28, 624-636 (2021) [2] R. Temperton et al. “Dip-and-Pull Ambient Pressure Photoelectron Spectroscopy as a Spectroelectrochemistry Tool for Probing Molecular Redox Processes.” Journal of Chemical Physics 157 (24): 244701 (2022) [3] I. Källquist et al. “Potentials in Li-Ion Batteries Probed by Operando Ambient Pressure Photoelectron Spectroscopy.” ACS Applied Materials and Interfaces 14 (5): 6465–75 (2022) [4] A. Larsson et al. “In Situ Quantitative Analysis of Electrochemical Oxide Film Development on Metal Surfaces Using Ambient Pressure X-Ray Photoelectron Spectroscopy: Industrial Alloys.” Applied Surface Science 611: 155714 (2023) Figure 1
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Dravid, Vinayak P. "Bicrystallography and electron diffraction." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 702–3. http://dx.doi.org/10.1017/s0424820100149349.
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Traditionally grain (or phase) boundaries have been modelled using coincidence site lattice (CLS)-type geometrical treatments. However, CSL utilizes only the latticetranslational symmetry of the crystals and is not applicable to nonsymmorphic crystals or in cases where the point group symmetry elements are important. Pond and coworkers, in an elegant series of papers proposed a complete geometric description of bicrystal containing an interface, i.e. bicrystallography. The use and application of bicrystallography has important implications for interface/surface structure, thin film growth and small particle studies.Theoretical development of bicrystallography (or tricrystallography..etc.) is rather complete. However, same is not the case for experimental bicrystallography. There two important methods for bicrystal diffraction experiments: one is the plan-view technique, while the other involves edge-on interface parallel to the electron beam. Plan-view CBED can determine loss of symmetry due to RBT as demonstrated by Eaglesham et al. Dravid et al. used plan-view CBED to probe the symmetry of NiO-ZrO2(CaO) eutectic interfaces.
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Wakamiya, Atsushi. "(Invited) Modification of Perovskite Layer for Efficient Perovskite Solar Cells." ECS Meeting Abstracts MA2024-02, no. 19 (2024): 1723. https://doi.org/10.1149/ma2024-02191723mtgabs.
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Perovskite solar cells are expected as promissing photovoltaics, offering a path to highly efficient solar energy conversion.1–4 Surface modification of perovskite layer is crucial to improve device performance and durability. In this talk, our recent progress on the development of charge collecting materials and surface modification with dipole strategy will be shown. Optimized Carrier Extraction at Interfaces 4-7 Carrier extraction in mixed tin–lead perovskite solar cells is improved by modifying the top and bottom perovskite surfaces with ethylenediammonium diiodide and glycine hydrochloride, respectively. Trap densities in the perovskite layers are reduced as a result of surface passivation effects and an increase in film crystallinity. In addition, the orientated aggregation of the ethylenediammonium and glycinium cations at the charge collection interfaces result in the formation of surface dipoles, which facilitate charge extraction. As a result, the treated mixed tin–lead perovskite solar cells showed improved performance, with a fill factor of 0.82 and a power conversion efficiency up to 23.6%.5 The unencapsulated device also shows improved stability under AM1.5G, retaining over 80% of the initial efficiency after 200 h continuous operation in inert atmosphere. Our strategy is also successfully applied to centimeter-scale devices, with efficiencies up to 21.0%. Tripodal Hole-Collecting Monolayer Materials 8 Hole-collecting monolayers have drawn attention in perovskite solar cell research due to their ease of processing, high performance, and good durability. Since molecules in the hole-collecting monolayer are typically composed of functionalized π-conjugated structures, hole extraction is expected to be more efficient when the π-cores are oriented face-on with respect to the adjacent surfaces. However, strategies for reliably controlling the molecular orientation in monolayers remain elusive. In this work, multiple phosphonic acid anchoring groups were used to control the molecular orientation of a series of triazatruxene derivatives chemisorbed on a transparent conducting oxide electrode surface. Using infrared reflection absorption spectroscopy and metastable atom electron spectroscopy, we found that multipodal derivatives align face-on to the electrode surface, while the monopodal counterpart adopts a more tilted configuration.8 The face-on orientation was found to facilitate hole extraction, leading to inverted perovskite solar cells with enhanced stability and high-power conversion efficiencies up to 25.0%. Acknowledgements : This work was partially supported by the JST-Mirai Program (JPMJMI22E2), NEDO ( JPNP21016), , the International Collaborative Research Program of ICR, Kyoto University, etc. T. Nakamura, A. Wakamiya, et al. "Sn(IV)-free Tin Perovskite Films Realized by In Situ Sn(0) Nanoparticle Treatment of The Precuarsor Solution", Nat. Commun. 2020, 11, 3008. S. Hu, J. A. Smikth, H. J. Snaith, A. Wakamiya, "Prospects for Tin-Containing Halide Perovskite Photovoltaics", Precis. Chem. 2023, 1, 69. T. Nakamura, Y. Kondo, N. Ohashi, M. A. Truong, R. Murdey, A. Wakamiya, et al. "Materials Chemistry for Metal Halide Perovskite Photovoltaics", Bull. Chem. Soc, Jpn. 2024, 97, uoad025. S. Hu, J. Thiesbrummel, J. Pascual, M. Stolterfoht, A. Wakamiya, H. J. Snaith, "Narrow Bandgap Metal Halide Perovskites for All-Perovskite Tandem Photovoltaics", Chem. Rev. 2024, in press. (DOI: 10.1021/acs.chemrev.3c00667) S. Hu, A. Wakamiya, et al. "Optimized Carrier Extraction at Interfaces for 23.6% Efficient Tin-Lead Perovskite Solar Cells", Energy Environ. Sci., 2022, 15, 2096. S. Hu, J. Pascual, A. Wakamiya, et al. "A Universal Surface Treatment for p-i-n Perovskite Solar Cells", ACS Appl. Mater. Interfaces, 2022, 14, 56290. S. Hu, H. J. Snaith, A. Wakamiya, et al. "Synergistic Surface Modification of Tin-Lead Perovskite Solar Cells", Adv. Mater. 2023, 35, 2208320. A. Truong, A. Wakamiya, et al. "Tripodal Triazatruxene Derivative as a Face-On Oriented Hole-Collecting Monolayer for Efficient and Stable Inverted Perovskite Solar Cells", J. Am. Chem. Soc. 2023, 145, 7528.
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Sartori, Andrea, Olaf M. Magnussen, and Bridget Murphy. "Role of Chemisorbing Species in Growth at Liquid Metal-Electrolyte Interfaces Revealed by in Situ X-Ray Scattering." ECS Meeting Abstracts MA2023-02, no. 55 (2023): 2666. http://dx.doi.org/10.1149/ma2023-02552666mtgabs.
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Liquid-liquid interfaces offer intriguing possibilities for nanomaterials growth. Especially, growth at liquid metal surfaces has recently received renewed interest. Here, fundamental interface-related mechanisms that control the growth behavior in these systems are studied for the case of Pb halide compound formation at the interface between liquid mercury electrode and aqueous salt solutions, using in situ X-ray reflectivity and grazing incidence X-ray diffraction, supplemented by electrochemical measurements and optical microscopy. The nucleation and growth of these compounds at potentials in the regime of Pb de-amalgamation was investigated in NaX + PbX2 (X = F, Cl, Br) to systematically explore the role of the halide species. X-ray reflectivity studies reveal the rapid formation of well-defined ultrathin precursor adlayers in Cl- and Br-containing solution. This adlayer formation is followed by subsequent quasi-epitaxial growth of Pb(OH)X bulk crystals, that are oriented with the c-axis along the surface normal. In contrast, growth in F-containing solution proceeds by slow formation of a more disordered deposit, resulting in random bulk crystal orientations on the Hg surface. A detailed structural analysis of the Pb(OH)Br and Pb(OH)Cl precursor adlayers reveals that they determine the orientation of the subsequently formed bulk crystals, with the arrangement in the adlayer providing a template. Together with our previous results on the pseudo-epitaxial growth of PbFBr on Hg (A. Elsen, et al., Proc.Nat.Acad.Sci., 2013, 110, 6663), these data reveal the decisive role of the interface chemistry, especially the strong chemisorption of the anions bromide and chloride, in steering the formation of these textured deposits at the liquid metal surface.
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Wang, Xuehang. "(Invited) Revealing Charge Storage Processes at the Interfaces of Supercapacitor Electrodes." ECS Meeting Abstracts MA2023-02, no. 5 (2023): 861. http://dx.doi.org/10.1149/ma2023-025861mtgabs.
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The fast development of electrochemical energy storage devices has revolutionized almost every aspect of modern life by enabling portable electronic devices, electric vehicles, and grid storage of renewable energy. To satisfy the growing industrial and consumer needs for energy storage systems with high output power and short recharge time, the electrode materials should have excellent high-rate performance.1 Electrical double-layer (EDL) capacitors exhibit high-rate capability and long-cycling life as they store charges electrostatically. Using ionic liquid (IL) as the electrolyte leads to a large voltage window but low capacitance. In this first session of the presentation, I will introduce a mathematical model to simulate the IL ion packing structure in nanopores. This model is capable of estimating the EDLC capacitance based on pore size distribution. Then, we further revealed that mixture IL ions can be selectively driven into the pores of different confinement levels, which was confirmed by solid-state NMR, and further explained by DFT simulation2. In the second part of the presentation, I will shift to pseudocapacitors, which are expected to have a much higher charge storage capacity than EDL capacitors and a much higher rate than batteries as they store energy through fast surface redox reactions.3 The emerging 2D material family, 2D transition metal carbides/nitrides MXenes, shows outstanding pseudocapacitive performance due to their ionophilicity, metallic conductivity, and highly reactive surfaces. The proper coupling between electrolyte and electrode is critical to increase energy and power density. In the organic electrolyte, we found that the solvent has a strong impact on the ion/solvent arrangement in 2D MXene material and hence the charge storage capability.4 In the aqueous electrolytes, we successfully introduced surface redox reactions to MXene electrodes by using the water-in-salt electrolytes and by adjusting the initial valence of Ti in Ti3C2 MXenes, which dramatically increases the capacitance of MXene in the neutral aqueous electrolytes5. References Simon, P.; Gogotsi, Y., Nat. Mater. 2020, 19 (11), 1151-1163. Wang, X.; Mehandzhiyski, A. Y.; et al., J. Am. Chem. Soc. 2017, 139 (51), 18681-18687. Fleischmann, S.; Mitchell, J. B.; et al., Chem. Rev. 2020, 120 (14), 6738-6782. Wang, X.; Mathis, T. S.; et al., Nat. Energy 2019, 4 (3), 241-248. Wang, X.; Mathis, T. S.; et al., ACS Nano 2021, 15 (9), 15274-15284.
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Yanina, Svetlana V., Matthew T. Johnson, Zhigang Mao, and C. Barry Carter. "On Devitrification of Monticellite (CaMgSiO4) Films Grown on (001)-Oriented Single-Crystal MgO." Microscopy and Microanalysis 4, S2 (1998): 590–91. http://dx.doi.org/10.1017/s1431927600023072.
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Silicate glasses are the most common constituents of intergranular phases which can be found in liquid-phase sintered ceramics [1]. Silicates are known to influence the structure of ceramic interfaces which, in turn, frequently affect mechanical properties of ceramic materials [2]. In earlier studies of silicate glasses on single-crystal alumina Ramamurthy et al [3] and Mallamaci [4] showed that the morphology of dewetted glass films and the mechanism of devitrification depend on the crystallographic orientation of the substrate surface. In continuation of these studies, results are presented on the dewetting behavior of monticellite (CaMgSi04) in contact with the (OOl)-oriented surface of single-crystal MgO. Due to the simplicity of sample preparation and availability of 3- dimensional topographic information, Atomic Force Microscopy (AFM) was used for surface characterization. These AFM results are complemented by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) data on the chemical composition and the structure of the glass-substrate interface.
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Martin, Nazario. "Gem-Dibromovinylenes: Highly Versatile Systems for On-Surface Synthesis." ECS Meeting Abstracts MA2024-01, no. 16 (2024): 1189. http://dx.doi.org/10.1149/ma2024-01161189mtgabs.
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The advent of the so-called On-Surface synthesis represents a new scenario where testing new reaction conditions affording disruptive materials impossible to be obtained by conventional synthetic chemistry. In this regard, we have reported an unprecedented chemical reaction from tetrabromo-p-quinodimethanes (TBQs) which, by heating on gold surface, has allowed to obtain a variety of new 1D π-conjugated polymers,[1] some of them exhibiting a quasimetallic behavior.[2] In this presentation, new designed organic molecules endowed with gem-dibromovinylene units have been synthesized with the aim of broadening the scope of this highly reactive functional group to other on-surface chemical reactions.[3] Thus, new different polymers or molecular systems will be presented and discussed.[4] References [1] A. Sánchez-Grande, et al., "On-surface synthesis of ethynylene bridged anthracene polymers", Angew. Chem. Int. Ed., 2019, 58, 6559-6563. [2] Cirera, B., et al., “Tailoring topological order and π-conjugation to engineer quasi-metallic polymers”. Nat. Nanotechnol. 2020, 15, 437–443. [3] Sánchez-Grande, et al., "Surface-assisted Synthesis of N-substituted π-Conjugated Polymers" Adv. Sci., 2022, - advs.202200407R1 [4] E. Pérez-Elvira, et al., "Generating Antiaromaticity: Thermally-selective Skeletal Rearrangements at Interfaces", Nat. Synth., 2023, NATSYNTH-22121246B.
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GLIMM, TILMANN, and H. G. E. HENTSCHEL. "ON ISOCONCENTRATION SURFACES OF THREE-DIMENSIONAL TURING PATTERNS." International Journal of Bifurcation and Chaos 18, no. 02 (2008): 391–406. http://dx.doi.org/10.1142/s0218127408020355.
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We consider three-dimensional Turing patterns and their isoconcentration surfaces corresponding to the equilibrium concentration of the reaction kinetics. We call these surfaces equilibrium concentration surfaces (EC surfaces). They are the interfaces between the regions of "high" and "low" concentrations in Turing patterns. We give alternate characterizations of EC surfaces by means of two variational principles, one of them being that they are optimal for diffusive transport. Several examples of EC surfaces are considered. Remarkably, they are often very well approximated by certain minimal surfaces. We give a dynamical explanation for the emergence of Scherk's surface in certain cases, a structure that has been observed numerically previously in [De Wit et al., 1997].
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Liu, Yang, Yuxiao He, Enbo Zhu, Jin Huang, and Yu Huang. "Periodic 1D Assembly of Diblock Hetero-Nanowires As Tandem Electrocatalysts." ECS Meeting Abstracts MA2024-02, no. 67 (2024): 4670. https://doi.org/10.1149/ma2024-02674670mtgabs.
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There has been a growing interest in tandem electrocatalysts with unique interfaces and synergetic functions, which have been reported to exhibit outstanding performance in activity[1], selectivity[2], and stability[3]. Besides the development of monolithic tandem nanostructures, nanoparticle (NP) assembly provides a more desirable and controllable strategy to elaborately design novel nanocatalysts for various applications. Compared with two-dimensional (2D) and 3D tandem nanostructures, 1D tandem nanostructures have attracted more interest due to their high electrochemical surface areas, great atomic utilization, and outstanding structural stability, all of which are highly favored to achieve better electrocatalytic activity and stability. However, controllable 1D NP assembly is still challenging to achieve due to its relatively high surface energy and anisotropy, not to mention the creation of periodic 1D heterogeneous nanostructures with intimate interfaces and clean surfaces. In this work, we report a strategy to obtain periodic Pt-Au nanowires (NWs) by the assembly of Pt-Au Janus NPs with the assistance of peptide T7 (Ac-TLTTLTN-CONH2). We further demonstrate that the Pt-Au NWs show highly improved catalytic performance in the methanol oxidation reaction (MOR), a 5.3 times higher specific activity and a 2.5 times higher mass activity than that of the current state-of-the-art commercial Pt/C catalyst. The charge transfer at the interfaces of adjacent Pt and Au regions could weaken the binding energy between Pt and CO or CO-like intermediates, contributing to the enhancement of activities in MOR. More importantly, the periodic Pt-Au NWs exhibit outstanding stability in MOR, where the mass activity of Pt-Au NWs after 1000 cycles retains 93.9%, much higher than that of the commercial Pt/C (30.6%). We believe that this strategy to design and obtain periodic NWs by the assembly of Janus NPs is universal and transformative to diverse electrocatalytic reactions to achieve synergistic effects and intimate interfaces with high catalytic activity.[4][5] In conclusion, we have obtained periodic Pt-Au NWs by the assembly of Pt-Au Janus NPs with the assistance of peptides and demonstrated their outstanding activities and stability in MOR. This research presents a strategy to develop periodic heterogeneous nanowires with intimate interfaces and synergistic effects by the 1D assembly of Janus NPs, which offers an opportunity to design and program periodic 1D tandem catalysts. References Liu, Huibing, et al. "Dual active site tandem catalysis of metal hydroxyl oxides and single atoms for boosting oxygen evolution reaction."Applied Catalysis B: Environmental 297 (2021): 120451. Morales-Guio, Carlos G., et al. "Improved CO2 reduction activity towards C2+ alcohols on a tandem gold on copper electrocatalyst."Nature Catalysis 10 (2018): 764-771. You, Xingchao, et al. "Ru-Ni alloy nanosheets as tandem catalysts for electrochemical reduction of nitrate to ammonia."Nano Research (2024): 1-10. Shao, Qi, Pengtang Wang, and Xiaoqing Huang. "Opportunities and challenges of interface engineering in bimetallic nanostructure for enhanced electrocatalysis."Advanced Functional Materials 3 (2019): 1806419. Ma, Jiamin, et al. "Recent advances in application of tandem catalyst for electrocatalytic CO2 reduction."Molecular Catalysis 551 (2023): 113632.
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Huynh, Kenny, Michael Evan Liao, Thomas Pfeifer, et al. "Improved Thermal Boundary Conductance in Annealed Direct Wafer Bonded Si-Ge." ECS Meeting Abstracts MA2023-02, no. 33 (2023): 1606. http://dx.doi.org/10.1149/ma2023-02331606mtgabs.
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The evolution of structural and thermal properties of wafer bonded Si|Ge with annealing is investigated in this study. Theoretical work suggests that the thermal boundary conductance between amorphous Si and Ge provide improved thermal properties as compared to a crystalline Si to Ge interface, and wafer bonded systems provides a fabrication method to experimentally test this theory [1]. EVG® ComBond® equipment was used for bonding under high vacuum (~10-8 mtorr) at room temperature to remove unwanted native surface oxides [2-4]. The bombardment of the surfaces prior to bonding produces an amorphous region at the bonded interface that has been seen in many other bonded systems [5,6]. In the as-bonded sample, high resolution scanning transmission electron microscopy revealed a ~1.2 nm amorphous region at the bonded interface. Subsequent annealing was done in an effort to recrystallize the amorphous interface. Previous work has shown that recrystallization between Si|Si wafer bonded samples occurred when annealed at 450 °C for 12 hours [3]. After annealing at 600 °C for 2 hours, the amorphous interface was observed to decrease to ~0.9 nm. Complete recrystallization is observed when the sample was annealed at 600 °C for 48 hours. Preliminary thermal results show that the thermal boundary conductance (TBC) of the as bonded sample is 47 ± 5 MW/(m2K). The TBC for the sample annealed at 600 °C for 48 hours is 94 ± 5 MW/(m2K), an improvement by a factor of two compared to the as-bonded interface. These results demonstrate that the TBC can be improved through annealing of the interface and that improvements due to an amorphous-amorphous interface do not dominate the thermal boundary conductance in this system. We consider that the improvements are due to recrystallization of the interface and/or to increased interdiffusion, which has been observed to increase TBC in epitaxially grown Si-Ge interfaces [7]. K. Gordiz, et al., J. Appl. Phys., 121(2), p.025102 (2017) V. Dragoi, et al., ECS Trans., 86(5), 23 (2018) C. Flötgen, et al., ECS Trans., 64(5), 103 (2014) M.E. Liao, et al., ECS Trans., 86(5), 55 (2018) Y. Xu, et al., Ceramics International, 45, 6552 (2019) F. Mu, et al., Appl. Surf. Sci., 416, 1007 (2017) Z. Cheng, et al., Nature communications, 12(1), p.6901 (2021) Figure 1
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BANNER, MICHAEL L., and WILLIAM L. PEIRSON. "Tangential stress beneath wind-driven air–water interfaces." Journal of Fluid Mechanics 364 (June 10, 1998): 115–45. http://dx.doi.org/10.1017/s0022112098001128.
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The detailed structure of the aqueous surface sublayer flow immediately adjacent to the wind-driven air–water interface is investigated in a laboratory wind-wave flume using particle image velocimetry (PIV) techniques. The goal is to investigate quantitatively the character of the flow in this crucial, very thin region which is often disrupted by microscale breaking events. In this study, we also examine critically the conclusions of Okuda, Kawai & Toba (1977), who argued that for very short, strongly forced wind-wave conditions, shear stress is the dominant mechanism for transmitting the atmospheric wind stress into the water motion – waves and surface drift currents. In strong contrast, other authors have more recently observed very substantial normal stress contributions on the air side. The availability of PIV and associated image technology now permits a timely re-examination of the results of Okuda et al., which have been influential in shaping present perceptions of the physics of this dynamically important region. The PIV technique used in the present study overcomes many of the inherent shortcomings of the hydrogen bubble measurements, and allows reliable determination of the fluid velocity and shear within 200 μm of the instantaneous wind-driven air–water interface.The results obtained in this study are not in accord with the conclusions of Okuda et al. that the tangential stress component dominates the wind stress. It is found that prior to the formation of wind waves, the tangential stress contributes the entire wind stress, as expected. With increasing distance downwind, the mean tangential stress level decreases marginally, but as the wave field develops, the total wind stress increases significantly. Thus, the wave form drag, represented by the difference between the total wind stress and the mean tangential stress, also increases systematically with wave development and provides the major proportion of the wind stress once the waves have developed beyond their early growth stage. This scenario reconciles the question of relative importance of normal and tangential stresses at an air–water interface. Finally, consideration is given to the extrapolation of these detailed laboratory results to the field, where the present findings suggest that the sea surface is unlikely to become fully aerodynamically rough, at least for moderate to strong winds.
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Kim, Kyung Sung, Moo Hyun Kim, and Jong-Chun Park. "Development of Moving Particle Simulation Method for Multiliquid-Layer Sloshing." Mathematical Problems in Engineering 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/350165.
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The mixed oil and gas including water and sand are extracted from well to offshore structure. This mixed fluid must be separated for subsequent processes by using wash tanks or separators. To design such a system, a proper numerical-prediction tool for multiphase fluids is required. In this regard, a new moving particle simulation (MPS) method is developed to simulate multiliquid-layer sloshing problems. The new MPS method for multifluid system includes extra search methods for interface particles, boundary conditions for interfaces, buoyancy-correction model, and surface-tension model for interface particles. The new particle interaction models are verified through comparisons with published numerical and experimental data. In particular, the multiliquid MPS method is verified against Molin et al’s (2012) experiment with three liquid layers. In case of excitation frequency close to one of the internal-layer resonances, the internal interface motions can be much greater than top free-surface motions. The verified multiliquid MPS program is subsequently used for more nonlinear cases including multichromatic multimodal motions with larger amplitudes, from which various nonlinear features, such as internal breaking and more particle detachment, can be observed. For the nonlinear case, the differences between with and without buoyancy-correction and surface-tension models are also demonstrated.
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Olejnik, Adrian, Michal Sobaszek, Maria Brzhezinskaya, Mateusz Ficek, and Robert Bogdanowicz. "Electrochemistry and Electronic Structure of the Deuterium-Grown Boron-Doped Diamond Interfaces." ECS Meeting Abstracts MA2023-02, no. 57 (2023): 2784. http://dx.doi.org/10.1149/ma2023-02572784mtgabs.
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Integration of the first principles quantum mechanical simulations with electrochemistry represents a difficult research area due to the complexity and large size of real systems and computational limitations. On the one hand it is highly desirable to be able to predict electrochemical properties of materials and systems from simulations to limit the money expenditure for experimental work and accelerate applications [1]. On the other hand, utilization of ab-initio simulations to understand the experimentally observed phenomena is also required to embed them into a solid theoretical framework. To fulfill this task, several multiscale approaches are used with the density functional theory (DFT) being fundamental tool for investigation of electronic structure. DFT results can be further extended to build forcefields used in molecular dynamics (MD) [2] for larger scale simulations and non-equillibrium Green's functions for investigations of electronics and spintronics of nanodevices [3]. Semiconductor electrochemistry is one of the most important areas to explore this experiment-theory interface because of the necessity to develop new materials for photovoltaics, photoelectrochemistry, energy storage and conversion. The purpose of the following talk is to show the power of this paradigm by elucidation of the deuterium-grown boron doped diamond (BDD-D) material [4]. A brief introduction to the material synthesis, chemical and physical properties is provided exploiting the synchrotron data of X-Ray absorption spectroscopy and X-Ray photoelectron spectroscopy. Then, a strong emphasis is put into merging the (photo)electrochemical data with the first principle results for better understanding of charge transfer phenomena in the nanoscale. Specifically, DFT calculations of projected local density of states clearly show the presence of highly occupied surface states on the (111) plane of BDD-D in contrast to its standard hydrogen-grown counterpart (BDD-H). The resulting surface states are capable of photocurrent generation in the visible light, which is strongly magnified in BDD-D. Moreover, photoelectrochemical measurements evidenced that photocurrents can be positive or negative depending on the bias - despite BDD being a p-type semiconductor. These confirm a profound role of surface states in the semiconductor electrochemistry and capability of photoinduced charge transfer in the modified materials. The proposed picture shines some new light on the commonly established paradigm of band bending as the key factor driving surface properties of the nanodiamond surfaces [5]. Figure. SEM images of a) BDD@D and b) BDD@H; c) grain size distribution among two samples; d) XRD patterns of the diamond films deposited in the D2/CH4 and H2/CH4 gas mixtures. Reflections at 2θ around 44°, 75°, and 91° correspond to the (111), (220), and (311) diamond lattice planes, respectively. Doubling of the reflections is related to the presence of Kα1 and Kα2 wavelengths in the X-ray radiation [4]. Acknowledgements: M.S., M.B., and M.F. thank Helmholtz-Zentrum Berlin (HZB) for the allocation of synchrotron radiation beamtime at HZB (Germany). M.S. gratefully acknowledges the financial support of these studies from the Gdansk University of Technology through the DEC-02/2021/IDUB/ II.1/AMERICIUM grant under the Americium – “Excellence Initiative – Research University” program. R.B. acknowledges the funding from the National Science Centre, Poland under the OPUS call in the Weave programme (Project number: 2021/43/I/ST7/03205). References: [1] Zhao, Shuangliang, et al. "Unified framework of multiscale density functional theories and its recent applications." Advances in Chemical Engineering. Vol. 47. Academic Press, 2015. 1-83. [2] Le, Jia-Bo, and Jun Cheng. "Modeling electrochemical interfaces from ab initio molecular dynamics: water adsorption on metal surfaces at potential of zero charge." Current Opinion in Electrochemistry 19 (2020): 129-136. [3] Datta, Supriyo. Electronic transport in mesoscopic systems. Cambridge university press, 1997. [4] Sobaszek, Michał, et al. "Highly Occupied Surface States at Deuterium‐Grown Boron‐Doped Diamond Interfaces for Efficient Photoelectrochemistry." Small (2023): 2208265. [5] Kono, Shozo, et al. "Carbon 1s X-ray photoelectron spectra of realistic samples of hydrogen-terminated and oxygen-terminated CVD diamond (111) and (001)." Diamond and Related Materials 93 (2019): 105-130. Figure 1
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Lomonaco, Quentin, Karine Abadie, Jean-Michel Hartmann, et al. "Soft Surface Activated Bonding of Hydrophobic Silicon Substrates." ECS Meeting Abstracts MA2023-02, no. 33 (2023): 1601. http://dx.doi.org/10.1149/ma2023-02331601mtgabs.
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Surface Activated Bonding (SAB) is interesting for strong silicon to silicon bonding at room temperature without any annealing needed, afterwards (1). Although it is a well-known technique, the activation step, in particular, is scarcely documented. This paper offers insights about the impact of soft activation parameters on the amorphous region at the bonding interface. In addition, the adherence energy of hydrophobic silicon bonding with SAB is quantified to better understand bonding mechanisms. With very low dose and acceleration activation parameters, the surface preparation prior to bonding becomes of paramount importance. Indeed, the silicon native oxide is typically removed during the activation step. The thin amorphous silicon region is a side effect of this singular surface preparation(2). In order to work around this potential roadblock, we used instead hydrophobic surface preparation to remove the native oxide, before entering into the activation step. Two types of preparation were evaluated in this study. First, a standard “HF-Last” chemical treatment was used on standard silicon wafers. This treatment removed the silicon native oxide and passivated the surface with Si-H and, to a lesser extent, Si-F bonds (3). We otherwise used epitaxy-reconstructed silicon wafers with fully hydrophobic surfaces (4). Silicon native oxide was removed thanks to an ultra-pure H2 bake at 1100°C, 20 Torr for 2 minutes in an epitaxy chamber. Then, several tens of nm of Silicon were deposited at 950°C to obtain, after another H2 bake, a silicon surface fully passivated by hydrogen atoms with atomically smooth terraces and mono-atomic step edges. Our EVG®ComBond® bonding tool, operating under ultra-high vacuum (UHV), is equipped with an accelerated argon ion beam to perform the activation step. The softest functional settings, on our set up, are 50V (acceleration) and 26 mA (dose). After beam initialization, the two sets of substrates pass through the activation chamber. Activated substrates are then transferred to the bonding chamber within 5 minutes of handling. The exposure time in the activation chamber was evaluated, the aim being to remove adsorbed hydrogen atoms on the silicon surface without any amorphous silicon generation. Different characterization techniques such as transmission electron microscopy or FTIR-MIR were used to quantify the amorphous layer formation and the potential Si-H bonds remaining (after activation). The adherence energy of the bonded pair was measured by a double cantilever beam method under prescribed displacement control in anhydrous atmosphere (5). Figure 1 shows the adherence energy (Gc=2γc) in mJ/m² as a function of activation exposure time with soft activation parameters for both wafer preparations. The 0s reference bonding was conducted without passing through the activation module. We then had very low adherence energies, around 50 mJ/m², as expected for standard hydrophobic silicon wafer bonding under UHV (6). Upon Ar+ exposure, behaviors were very different depending on surface preparation. The adherence energy barely increased with the Ar+ exposure time for “HF-Last” surfaces. Meanwhile, even 1s of exposure to Ar+ had a definite impact on the adherence energy of epi-reconstructed, atomically smooth silicon surfaces, which was definitely higher. The maximum difference between both wafer preparations occurred for 30 up to 60 seconds exposure times. This indicate a change in the bonding mechanism as the comparatively high roughness of the “HF-Last” silicon wafer started to be counter-balanced by activation. The experimental set up, the manufacturing process, as well as further characterizations will be presented. Cross-sectional TEM imaging of the bonding interface, FTIR-MIR and AFM measurements after surface preparation will help us better understand the specificities of such soft activation process on the SAB of hydrophobic surfaces. The impact of the amorphous silicon layer on bonding will be discussed. Suga T et al. STRUCTURE OF A1-A1 A N D A1-Si3N4 INTERFACES BONDED AT ROOM TEMPERATURE BY MEANS OF THE SURFACE ACTIVATION METHOD. Acta Metallurgica et Materialia 1992. Takagi H et al. Surface activated bonding of silicon wafers at room temperature. Appl Phys Lett. 1996. Abbadie A et al. Low thermal budget surface preparation of Si and SiGe. Appl Surf Sci. 2004. Sordes D et al. Nanopackaging of Si(100)H Wafer for Atomic-Scale Investigations. 2017. Maszara WP et al. Bonding of silicon wafers for silicon‐on‐insulator. J Appl Phys. 15 nov 1988;64(10):4943-50. Tong QY et al. The Role of Surface Chemistry in Bonding of Standard Silicon Wafers. J Electrochem Soc. 1997. Figure 1
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Soligo, Giovanni, Alessio Roccon, and Alfredo Soldati. "Breakage, coalescence and size distribution of surfactant-laden droplets in turbulent flow." Journal of Fluid Mechanics 881 (October 24, 2019): 244–82. http://dx.doi.org/10.1017/jfm.2019.772.
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In this work, we compute numerically breakage/coalescence rates and size distribution of surfactant-laden droplets in turbulent flow. We use direct numerical simulation of turbulence coupled with a two-order-parameter phase-field method to describe droplets and surfactant dynamics. We consider two different values of the surface tension (i.e. two values for the Weber number, $We$, the ratio between inertial and surface tension forces) and four types of surfactant (i.e. four values of the elasticity number, $\unicode[STIX]{x1D6FD}_{s}$, which defines the strength of the surfactant). Stretching, breakage and merging of droplet interfaces are controlled by the complex interplay among shear stresses, surface tension and surfactant distribution, which are deeply intertwined. Shear stresses deform the interface, changing the local curvature and thus surface tension forces, but also advect surfactant over the interface. In turn, local increases of surfactant concentration reduce surface tension, changing the interface deformability and producing tangential (Marangoni) stresses. Finally, the interface feeds back to the local shear stresses via the capillary stresses, and changes the local surfactant distribution as it deforms, breaks and merges. We find that Marangoni stresses have a major role in restoring a uniform surfactant distribution over the interface, contrasting, in particular, the action of shear stresses: this restoring effect is proportional to the elasticity number and is stronger for smaller droplets. We also find that lower surface tension (higher $We$ or higher $\unicode[STIX]{x1D6FD}_{s}$) increases the number of breakage events, as expected, but also the number of coalescence events, more unexpected. The increase of the number of coalescence events can be traced back to two main factors: the higher probability of inter-droplet collisions, favoured by the larger number of available droplets, and the decreased deformability of smaller droplets. Finally, we show that, for all investigated cases, the steady-state droplet size distribution is in good agreement with the $-10/3$ power-law scaling (Garrett et al., J. Phys. Oceanogr., vol. 30 (9), 2000, pp. 2163–2171), conforming to previous experimental observations (Deane & Stokes, Nature, vol. 418 (6900), 2002, p. 839) and numerical simulations (Skartlien et al., J. Chem. Phys., vol. 139 (17), 2013).
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Zazpe, Raul, Hanna Sopha, Mouli Thalluri, et al. "(Invited) Atomic Layer Deposition on 1D Nanomaterials for Various Applications." ECS Meeting Abstracts MA2023-02, no. 29 (2023): 1441. http://dx.doi.org/10.1149/ma2023-02291441mtgabs.
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One-dimensional nanomaterials – materials with one dimension outside the nanoscale, further noted as 1D NMs – represent a class of very important nanomaterials with continuously increasing importance. Due to their intrinsic features, unique properties and diversity of functionalities, they count among the most widely studied materials nowadays. While considerable research efforts have been spent to synthesize various 1D NMs (e.g. nanopores, nanotubes or nanofibers), limited efforts have been devoted to surface modification and property tailoring of these materials. However, it is their surface that comes into direct contact with various media (air, gases, liquids, solids) and influences the reactivity, stability and biocompatibility of these materials. The surface and aspect ratio (defined as their diameter to length ratio) influence the performance of these materials in various applications. Considering these facts, it is more relevant to tailor the surface of these materials and to be able to influence their properties and reactivity at the nanoscale, rather than to deal with tailoring their own bulk material composition. The focus of this presentation is on the modification of two types of 1D nanomaterials – nanotubes and nanofibers. Numerous techniques can be utilized for this purpose, such as for example wet chemical or physical deposition techniques. However, it is only the Atomic Layer Deposition (ALD) that is capable of really uniform and homogenous coating of these 1D nanomaterials, in particular those of very high-aspect ratio. The presentation will be mainly focused on modification of TiO2 nanotube layers and various nanofibers of different aspect ratios via ALD. Experimental details and some very recent application examples in photocatalysis, catalysis, sensors, batteries, nanorobots, etc. [1-11] and structural characterizations of these modified materials will be discussed. Sopha et al (2017), Appl. Mater. Today, 9, 104. Sopha et al. (2018), Electrochem. Commun.,97, 91. Ng et al. (2017), Adv. Mater. Interfaces, 1701146. Dvorak et al. (2019), Appl. Mater. Today, 14, 1. Sopha et al. (2019), FlatChem 17, 100130. Motola et al. (2019), Nanoscale 11, 23126. Ng et al. (2020), ACS Appl. Mater. Interfaces, 12, 33386. Motola et al. (2020) ACS Appl. Bio Mater. 3, 6447. Rihova & M. Knez & J. M. Macak et al. (2021), Nanoscale Adv., 3, 4589 Galstyan, T. Djenizian, J. M. Macak (2022), Appl. Mater. Today, 29, 101613 Villa & M. Pumera & J. M. Macak et al. (2022), Small, 2106612
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Boz, Emre Burak, Ronald de Bruijne, and Antoni Forner-Cuenca. "Exploring Conductive Polymer Coatings to Target Reaction Selectivity in Aqueous All-Iron Redox Flow Batteries." ECS Meeting Abstracts MA2023-02, no. 59 (2023): 2888. http://dx.doi.org/10.1149/ma2023-02592888mtgabs.
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An energy grid that relies on wind and solar farms requires the installation of large-scale energy storage systems to balance their fluctuating output. Especially for developing countries, wide adoption of renewables is coupled to progress in sustainable and cost-effective storage technologies.1 From this perspective, aqueous all-iron redox flow batteries (AIRFBs) stand out as a promising technology, owing to the earth-abundance and low-cost of iron, along with its environmental and operational safety. In this battery, iron is utilized in its three oxidation states (Fe0, Fe2+ and Fe3+) and the negative electrode leverages the iron plating/stripping reactions to sustain charge and discharge. However, the standard potential of iron plating is 0.44 V below the hydrogen evolution reaction (HER), which causes faradaic losses during the charging stage and increases the pH of the solution.2 The catalytic activity of iron towards hydrogen evolution and the precipitation of iron hydroxide at pH above 3.5 further complicates the operation of AIRFBs. Thus, the reaction selectivity of the negative electrode should be targeted to improve the operational time and efficiency. So far, research has focused on electrolyte engineering to hinder adsorption of hydrogen on surfaces or excluding water from the solvent shell of iron.2,3 Alternatively, interfacial engineering of electrode surfaces can be a promising strategy to tune the reaction selectivity, given that hydrogen adsorption and iron nucleation are interfacial phenomena. The challenge here is to prevent a new interface from being created by the plated iron as that would render the modified interface obsolete. We hypothesize that polymeric layers where iron deposition can take place within or underneath the polymer (akin to a solid electrolyte interphase of a Li-ion battery anode) would preserve the HER-inhibiting characteristics of the surface. Here, we propose conductive polymer interfaces to target reaction selectivity during the iron plating reaction. Conductive polymers have been used to engineer HER-inhibiting interfaces and as corrosion protection layers for metals.4,5 Furthermore, they can be conformally coated on porous electrodes, enabling their use in flow reactors.6 We selected two conductive polymer systems: poly(pyrrole) (PPy) owing to its iron-coordinating nitrogen moieties and poly(3,4-ethylenedioxythiophene) (PEDOT) owing to its high conductivity and stability.7 Furthermore, we employed three counterions of different size, chlorine (Cl-), p-toluenesulfonate (pTS-) and poly(styrenesulfonate) (PSS-), to direct the morphology of the coating, resulting in six different polymer systems. On glassy carbon electrodes, all polymers significantly hinder HER at potentials as low as -1.5 V (vs Ag/AgCl) where heavy bubble formation is observed on bare electrodes (Figure 1). To assess the selectivity of the coatings on carbon paper substrates, we are developing an electrochemical protocol with successive plating/stripping cycles that is representative of battery operation. Preliminary results show that all polymer systems hinder the HER, but also the Fe-plating reaction, resulting in lower plating currents than the bare carbon paper electrodes. To validate the methodology, we compare the electrochemically obtained reaction selectivity values with the ones from gravimetric analysis. The ideal polymeric interfaces should inhibit the HER without largely impacting the Fe-plating kinetics, which motivates research into the relationship between the coating thickness, conductivity, and the faradaic efficiency. To understand the plating morphology on polymeric coatings, we investigate the spatial distribution of iron on the surface and the cross-section of plated electrodes using microscopic methods. Hydrogen evolution and limited durability due to complex plating reactions hamper the broad implementation of all-iron redox flow batteries and we hope to tackle these challenges through interfacial electrode engineering. References Rahman et al., in Renewable Energy and Sustainability, Elsevier, 2022, pp. 347–376. Hawthorne et al., J. Electrochem. Soc. 2014, 162, A108. Liu et al., ACS Cent. Sci. 2022, 8, 729. Tian et al., J. Electrochem. Soc. 2013, 161, E23. Deshpande et al., J Coat Technol Res 2014, 11, 473. Boz et al., Adv Materials Inter 2023, 2202497. Mao et al., Energy Environ. Sci. 2011, 4, 3442. Figure 1
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Rapisarda, Matteo, Mattia Scagliotti, Antonio Valletta, Silvia Milita, and Luigi Mariucci. "(Invited) Influence of the Semiconductor Thin Film Morphologies on Dntt Organic Electronic Devices Performances." ECS Meeting Abstracts MA2024-01, no. 31 (2024): 1543. http://dx.doi.org/10.1149/ma2024-01311543mtgabs.
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Interest in organic semiconductors has grown enormously in the last few years, indeed their use in microelectronics is continuously rising up in a large range of fields, spanning from academic to industrial new applications [1]. They provide a large number of interesting properties that have pushed a gradual replacement of classical amorphous silicon-based devices with organic ones [2], as they promise to be the best candidates as drivers of the necessary green and digital transition and become the building blocks in a huge number of future applications. In most devices, particularly in OTFTs, the quality and properties of the interface between semiconductor and dielectric are of fundamental importance for the device electrical characteristics [3-4]. Dinaphtho [2,3-b:2′,3′-f] thieno [3,2-b] thiophene (DNTT)-based OTFTs are among the best-known devices as they provide good performances in terms of charge mobility, good stability as well as easy processing and they are particularly suitable to study deeper the role of insulator/semiconductor interface [5-6]. It has been widely reported that the best performances of the small molecule organic based transistors, in terms of charge mobility as well as stability, are obtained when the molecules align with their long axis almost perpendicular to the growth surface. The DNTT molecules deposited on SiO2, align to form a homogeneous film, which results to be highly crystalline and provides good transport properties. However, in DNTT-based OTFTs different insulator surfaces, above which the active layer is grown, can provide different properties in terms of morphology and surface energy so that the electrical performances of the resulted devices can span in a wide range [7]. In this work, we have studied the growth of DNTT semiconductor thin films on two different dielectric materials relating the ordered DNTT thin film structure to the OTFTs' electrical characteristics. OTFTs have been fabricated with Bottom Gate Top Contact (BGTC) configuration using thermal SiO2 or a double layer of SiO2/CytopTM as gate dielectrics. Semiconductor thin films, with thicknesses ranging from 3 nm to 50 nm, were detailed analyzed with high resolution AFM and XRD measurements (Fig. 1a, b, c, d) for different growth conditions to understand the morphologies of the films starting by the very first ordered layers of DNTT semiconductors. Our measurements show that DNTT molecules on SiO2 and Cytop pack into ordered structures placing themselves with their long axis perpendicular to the plane of the substrate (edge-on). However, in the case of DNTT on SiO2, a portion of ordered molecules can lie horizontally on the substrate (face-on). This causes an increase of defective states for the majority carriers in the conductive channel of the transistor, with a consequent reduction of the field-effect mobility (Fig. 1a, b). Numerical simulations were performed to analyze the effects of different semiconductor film morphologies on the electrical characteristics of the OTFTs. We also show that the morphological semiconductor differences lead to better performances for organic phototransistors based on DNTT/Cytop interface [8]. [1] C. Wang et al., Chemical reviews 2012, 112 (4), 2208-2267. [2] Y. Bonnassieux et al., Flexible and Printed Electronics 2021, 6 (2), 023001. [3] H. I. Un et al., Advanced Science 2019, 6 (20), 1900375. [4] H. Sirringhaus et al., Advanced materials 2014, 26 (9), 1319-1335. [5] H. Chang et al., Org. Electron., 2015, 22, 86-91. [6] Q. Wang et al., ACS applied materials & interfaces 2018, 10 (26), 22513-22519. [7] M. Geiger et al., Advanced Materials Interfaces 2020, 7 (10), 1902145. [8] S. Calvi, et al., Org. Electron., 2022, 102, 106452. Figure 1
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Minamimoto, Hiro, Futa Shiga, and Minoru Mizuhata. "(Invited) Changes in Electric Double-Layer Structures Under Localized Surface Plasmon Excitation." ECS Meeting Abstracts MA2024-01, no. 35 (2024): 1951. http://dx.doi.org/10.1149/ma2024-01351951mtgabs.
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For the visible light energy conversion, the localized surface plasmon resonance (LSPR), which is the collective oscillations of free electrons, should be promising. With the excitation of LSPR, the highly localized electric field generates in the vicinity of metal nanostructures. It is interesting that various unique photo-response properties, such as chemical reactions or molecular excitations, can be observed due to the enhancement of light-matter interaction.[1] To understand and control such mediated chemical reactions or electrochemical reactions, the precise understanding about the electrified interfaces of plasmonic nanostructures should be required. Especially in the electrochemical system, the electric double layer is formed due to the difference in electrochemical potential between the metal interface and solution. The study of the surface potential is important for the design of chemical reactions because the surface potential at the liquid-solid interface is dependent on the physical properties of the systems. The zeta potential which is the potential of the slipping surface near the Stern layer of the diffusion layer could provide such information. From this point of view, in this study, we investigated the electric double-layer structures through the examination of the zeta potential under LSPR excitation condition. To obtain the zeta potential, we have performed the streaming potential method using Au nanoisland structures under visible light illuminations to excite the LSPR. It was interesting that the zeta potential was drastically changes under the visible light illumination conditions. This zeta potential change indicates the changes in the electric double layer structures through the excitation of LSPR. Through the investigations of incident wavelength dependence or the substrate dependences, the effects for the LSPR excitations on the electric double layer structure have been revealed. The present work would provide the fundamental knowledge about the effect on the LSPR excitation at solid-liquid interfaces. [1] H. Minamimoto et al., Acc. Chem. Res., 2022, 55(6), 809.
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Ngene, Peter. "Interface Induced Fast Ion Conduction in Complex Hydride/Oxide Nanocomposites: Interplay between Hydride and Oxide Properties." ECS Meeting Abstracts MA2023-02, no. 5 (2023): 886. http://dx.doi.org/10.1149/ma2023-025886mtgabs.
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Solid-state electrolytes are crucial for next generation batteries with high energy density, long lasting and improved safety. The compatibility of most solid electrolytes with metallic anodes such as Li and Na metals, and cathodes such as sulfur, makes them suitable for high-capacity batteries (e.g., Li-S). They also address the safety concerns of current batteries by eliminating the flammable organic solvents in liquid electrolytes and by preventing/limiting dendrite formation. The lithium and sodium containing complex metal hydrides (e.g., LiBH4, NaBH4, LiCB11H12) have recently gained attention as solid-state electrolyte. They show high ionic conductivities but only at elevated temperatures (typically above 110 °C). Extending the high ionic conductivities to ambient temperatures is pivotal to the application of this fascinating class of solid electrolytes [1]. In this contribution, we will use LiBH4 and NaBH4 as examples to show that the ionic conductivities of complex hydrides can be greatly enhanced through interface effects resulting from the formation of nanocomposites with metal oxides. This strategy can lead to several orders of magnitude increase in the room temperature ionic conductivity [2]. Using DSC, DRIFT, solid-state NMR, and XRS (Xray Raman scattering), I will discuss how nanocomposite formation and presence of interfaces modifies either the phase stability, the defect concentration and/or leads to the formation of tertiary phase, and thereby increase profoundly the ion mobility of the complex hydrides. Systematic studies with different oxide nanoscaffolds and surface modified metal oxides, reveal that these effects can be optimized by tuning/engineering the nanostructure and interfaces in the nanocomposites. [3-4]. We will show that the effects also depend on a complex interplay between the stability of the metal hydride and surface properties of the metal oxide. Finally, the performance of some of the nanocomposite electrolytes in all-solid-state batteries, will be highlighted [5] References [1] L.M de Kort, P. Ngene et al. J. Journal of Alloys and Compounds 901 (2022) 163474 [2] D. Blanchard et al., Advanced Functional Material. 25 (2015), 182. [3] P. Ngene et al. Physical Chemistry Chemical Physics 21 (40), 22456-22466 [4] L.M de Kort, P. Ngene et al. Journal of Materials Chemistry A 8.39 (2020): 20687-20697 [5] D. Blanchard et al, J. Electrochem. Soc. (2016).
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Das, Prodip. "(Invited, Digital Presentation) Tuning Gas-Diffusion-Layer Surface Wettability for Polymer Electrolyte Fuel Cells." ECS Meeting Abstracts MA2022-01, no. 38 (2022): 1709. http://dx.doi.org/10.1149/ma2022-01381709mtgabs.
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In the present scenario of a global initiative toward securing global net-zero by mid-century and keeping 1.5 degrees within reach, polymer-electrolyte fuel cells (PEFCs) are considered to play an important role in the energy transition, particularly for the decarbonization of transit buses, trucks, rail transport, ships and ferries, and the residential heating sector. However, PEFCs are not economically competitive with the internal combustion engine powertrains [1]. Moreover, their durability standards in widely varying conditions have yet to be established and water management remains a critical issue for performance degradation and durability [1-3]. Thus, the mission of my research team is to conduct original research to make PEFCs economically viable and optimize their performance and durability [4,5]. In this talk, I will highlight our research on PEFC’s gas diffusion layer (GDL), as its interfaces with the flow channel and microporous layer play a significant role in water management. This research was aimed at selectively modifying GDL surfaces with a hydrophobic pattern to improve water transport and water removal from flow channels; thus, improving the durability and performance of PEFCs. Sigracet® GDLs were used as a base substrate and two different monomers, polydimethylsiloxane (PDMS) added with fumed silica (Si) and fluorinated ethylene propylene (FEP) were used to print a selective pattern on the GDL surfaces [6]. Both the additive manufacturing and spray coating techniques were utilized for creating the hydrophobic pattern on the GDL surfaces. The results of this study demonstrated a novel but simple approach to tune GDL surfaces with selective wetting properties and superhydrophobic interfaces that would enhance water transport. I will discuss some of these results and highlight how these results will benefit the water management of next-generation high-power PEFCs. This work was funded by the Engineering and Physical Sciences Research Council (EP/P03098X/1) and the STFC Batteries Network (ST/R006873/1) and was supported by SGL Carbon SE (www.sglcarbon.com). References [1] A.Z. Weber et al., "A critical review of modeling transport phenomena in polymer electrolyte fuel cells," J. Electrochem. Soc., vol. 161, pp. F1254-F1299, 2014. [2] A.D. Santamaria et al., "Liquid-water interactions with gas-diffusion layers surfaces," J. Electrochem. Soc., vol. 161, pp. F1184-F1193, 2014. [3] P.K. Das and A.Z. Weber, "Water management in PEMFC with ultra-thin catalyst-layers," ASME 11th Fuel Cell Science, Engineering and Technology Conference, Paper No. FuelCell2013-18010, pp. V001T01A002, 2013. [4] L. Xing et al., "Membrane electrode assemblies for PEM fuel cells: A review of functional graded design and optimization," Energy, vol. 177, pp. 445-464, 2019. [5] L. Xing et al., "Inhomogeneous distribution of platinum and ionomer in the porous cathode to maximize the performance of a PEM fuel cell," AIChE J., vol. 63, pp. 4895-4910, 2017. [6] D. Thumbarathy et al., "Fabrication and characterization of tuneable flow-channel/gas-diffusion-layer interface for polymer electrolyte fuel cells," J. Electrochem. Energy Convers. Storage, vol. 17, pp. 011010, 2020.
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TONG, S. Y., HUA LI, and H. HUANG. "SURFACE CRYSTALLOGRAPHY BY INVERTING DIFFRACTION SPECTRA." Surface Review and Letters 01, no. 02n03 (1994): 303–18. http://dx.doi.org/10.1142/s0218625x9400031x.
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New ideas on how to invert electron diffraction spectra to produce the atomic coordinates of surface region atoms are reviewed in this article. Some of the ideas are borrowed from optical holography while others are invented to deal with the strong multiple scattering and angular anisotropies present in electron diffraction in solids. The examples and references given in this and the accompanying two articles (by Heinz et al. and Wei et al. respectively) demonstrate that surface crystallography by data inversion is a viable method for a number of commonly used surface diffraction techniques.
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Hebert, Kurt. "Morphological Instability of Lithium Electrodeposition Due to Stress-Driven Interface Diffusion." ECS Meeting Abstracts MA2022-01, no. 1 (2022): 39. http://dx.doi.org/10.1149/ma2022-01139mtgabs.
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Morphological instability of the lithium-electrolyte interface is a critical problem limiting the development of lithium-metal negative electrodes for batteries. At high current densities approaching the diffusion-limited current density, dendrites form due to depletion of Li+ ions near the electrode surface (1). At lower current densities, unstable deposition produces whiskers (2). Whiskers are separated by typically several micrometers, and in contrast to dendrites grow by addition of Li atoms to their base or "root" (3). Experimental evidence indicates that whisker growth is fed by large-scale interface or grain boundary diffusion, and that whiskers relieve compressive stress in the metal generated by electrodeposition (4-7). The present study proposes that Li electrodeposition is destabilized by interface diffusion driven by compressive stress due to incorporation of Li atoms at grain boundaries. The competition between stress and stabilizing surface energy effects generates a surface pattern which determines (in part) whisker sites. A morphological instability model is formulated based on the Asaro-Tiller-Grinfel'd (ATG) surface instability on elastically stress solids (8). The model applies to deposits less than 1 micron thick for which elastic deformation is expected to dominate (9,10). The Li electrode is depicted by a three-layer elastic model consisting of a stress-free substrate (current collector) layer, a Li layer with uniform diffusion-induced in-plane stress, and top layer. The top layer can simulate submicron thickness solid-electrolyte interface (SEI) layers, or macroscopically thick polymer separators and solid electrolytes. The Li-top layer interface deforms by diffusion. Out-of-plane normal stress is included to simulate the effect of applied stress on the instability (11,12). For model calculations, the interface stress was estimated from neutron-depth-profiling measurements of Li diffusion into Cu current collectors (13). The measured Li incorporation was found to be consistent with a whisker spacing of several microns, in agreement with experimental results (3,6,14). Calculations showed that the instability is inhibited significantly by the use of substrates with elastic modulus much greater than that of Li. This substrate stiffness effect is consistent with experimental observations of Sn whiskers (15). The effect of a stress-free SEI layer on the instability was found to be negligible, due to its small thickness. Whisker growth was suppressed by macroscopically thick top layers with elastic modulus at least 10 times that of Li. No significant whisker inhibition was found at applied stress levels of ~ 1 MPa, which are found experimentally to stabilize deposition in Li films significantly exceeding 1 micron thickness (11,12). This effect may be due to an instability associated with viscoplastic rather than elastic deformation (16). REFERENCES P. Bai et al., Energy Environ. Sci., 9, 3221(2016). L Frenck et al., Front. Energy Res., 7, 115 (2016) A. Kushima et al., Nano Energy, 32, 271 (2017). J. H. Cho et al., Energy Storage Mater., 24, 281 (2020). X. Wang et al., Nat. Energy, 3, 227 (2018). A. A. Rulev et al., J. Phys. Chem. Lett., 11, 10511 (2020). E. Chason et al., Prog. Surf. Sci., 88, 103 (2013). B. J. Spencer et al., J. Appl. Phys., 73, 4956 (1993). C. Xu et al., Proc. Nat. Acad. Sci., 114, 57 (2017). L. Q. Zhang et al., Nat. Nanotechnol., 15, 94 (2020). A. J. Louli et al., J. Electrochem. Soc., 166, A1291 (2019). K. L. Harrison et al., ACS Appl. Mater. Interfaces, 13, 31668 (2021). S. Lv et al., Nat. Commun., 9, 2152 (2018). J. Steiger et al., J. Power Sources, 261, 112 (2014). B. Hutchinson et al., Mater. Sci. Forum, 467-470, 465 (2004). S. Narayan and L. Anand, J. Electrochem. Soc., 167, 040525 (2020).
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Yang, Keun-Hyeok. "Shear Stress-Relative Slip Relationship at Concrete Interfaces." Advances in Materials Science and Engineering 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/6475161.
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This study develops a simple and rational shear stress-relative slip model of concrete interfaces with monolithic castings or smooth construction joints. In developing the model, the initial shear cracking stress and relative slip amount at peak stress were formulated from a nonlinear regression analysis using test data for push-off specimens. The shear friction strength was determined from the generalized equations on the basis of the upper-bound theorem of concrete plasticity. Then, a parametric fitting analysis was performed to derive equations for the key parameters determining the shapes of the ascending and descending branches of the shear stress-relative slip curve. The comparisons of predictions and measurements obtained from push-off tests confirmed that the proposed model provides superior accuracy in predicting the shear stress-relative slip relationship of interfacial shear planes. This was evidenced by the lower normalized root mean square error than those in Xu et al.’s model and the CEB-FIB model, which have many limitations in terms of the roughness of the substrate surface along an interface and the magnitude of equivalent normal stress.