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Abahussain, Abdulaziz A. M., S. Z. J. Zaidi, M. H. Nazir, M. Raza, M. H. Nazir, and S. Hassan. "A DFT Study of Graphene as a Drug Carrier for Gemcitabine Anticancer Drug." Journal of New Materials for Electrochemical Systems 25, no. 4 (2022): 234–39. http://dx.doi.org/10.14447/jnmes.v25i4.a02.
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Research is being carried out worldwide for possible treatment of cancer. Graphene has been studied as a drug carrier for various cancer-related drugs [1-2]. In the present work, we apply theoretical models to study the electrons interactions, thermodynamic properties, and solvent interaction of the drug-carrier configuration. The stability of graphene means that it can be a nanocarrier in the biological system. The simulations result shows that graphene provides a stable base, where gemcitabine is a highly dissolvable and reactive drug. The adsorption of gemcitabine on the graphene was physical. The drug carrier configuration formed a highly impactful drug-carrier design.
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Graziano, Antimo, Shaffiq Jaffer, and Mohini Sain. "Graphene oxide modification for enhancing high-density polyethylene properties: a comparison between solvent reaction and melt mixing." Journal of Polymer Engineering 39, no. 1 (2018): 85–93. http://dx.doi.org/10.1515/polyeng-2018-0106.
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Abstract Graphene oxide (GO) was chemically modified in xylene with dodecyl amine and hydrazine monohydrate to obtain reduced functionalized graphene oxide (RFGO). Composites of high-density polyethylene (HDPE) and GO were made via solvent reaction, whereas both melt mixing and solvent reaction were used for HDPE-RFGO composites for comparison purposes. Elemental and thermal analysis showed the success of GO modification in grafting amine functionalities onto its structure and restoring most of the original graphene C=C bonds. A significant increase in mechanical properties, thermal stability, and crystallization behavior was observed for HDPE-RFGO (solvent) compared with HDPE and HDPE-GO, proving that homogeneous dispersion of RFGO in the polymer matrix and strong interactions between them resulted in facilitated stress transfer, delayed thermal degradation, and more efficient nucleating effect in inducing the crystal growth of HDPE. A comparison of HDPE-RFGO properties enhancement between the melt mixing method and the solvent reaction method showed that, apart from mechanical behavior, the RFGO contribution was the same, suggesting that the optimization of the ecofriendlier approach (melt) could eventually lead to its total use for the mass production of high-performance, cost-effective, and more environmentally friendly graphene-based thermoplastic polyolefin nanocomposites suitable for highly demanding industrial applications.
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Bake, Ieva, Liga Rampane, Ilze Balgale, Silvija Kukle, and Imants Adijans. "EVALUATION OF THE GRAPHENE DISPERSIONS FOR KEVLAR FABRICS FUNCTIONALIZATION OBTAINED BY THE LIQUID-EXFOLIATION OF GRAPHITE." ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference 1 (June 22, 2024): 70–77. http://dx.doi.org/10.17770/etr2024vol1.7985.
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The process where pristine graphite is subjected to a solvent treatment seems simple and scalable and has attracted the attention of researchers over many years. However, for successful exfoliation, overcoming the van der Waals attractions between the adjacent layers of graphite is necessary. Over time, several methods have been created to overcome the attraction between layers. Graphene’s liquid phase exfoliation (LPE) occurs due to the strong interactions between the solvent molecules and the basal planes of graphite, overcoming the energetic resistance to exfoliation and subsequent dispersion. Ultra sonication used for exfoliation can produce single or few layered graphene flakes. During sonication the sound waves propagate through liquid medium in alternating high- and low-pressure cycles, strong mechanical and thermal energy released by acoustic cavitation results in splitting up large particles into fine ones and dispersing them. Simultaneous insertion of solvent and/or intercalation molecules in between the graphite layers takes place supporting graphite separation into graphene layers. ; The dispersion capacity of graphene flakes depends on how appropriate the solvent properties are to the corresponding properties of graphene, such as surface tension, Hildebrand, and Hansen solubility parameters. Only certain solvents can disperse graphene well and form a dispersion appropriate for specific future applications. In addition, after exfoliation by ultra sonication graphene flakes aggregation due to the van der Waals attractions must be overcome to prepare in long-term stable dispersions of nanometres-size graphene sheets. ; The research has focused on the preparation of stable dispersion ready for transfer without intermediate processes to the Kevlar fabrics. An experimental comparison of the potentials of the 4 solvents for the application resulted in three corresponding to the intended use, two of them examined in detail, supplementing the composition of the LPE liquid medium with triethanolamine to obtain sufficient performance graphene coverage on Kevlar textile fibres.
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Liang, Yanyu, Dongqing Wu, Xinliang Feng, and Klaus Müllen. "Dispersion of Graphene Sheets in Organic Solvent Supported by Ionic Interactions." Advanced Materials 21, no. 17 (2009): 1679–83. http://dx.doi.org/10.1002/adma.200803160.
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Berisha, Avni. "Interactions between the Aryldiazonium Cations and Graphene Oxide: A DFT Study." Journal of Chemistry 2019 (February 26, 2019): 1–5. http://dx.doi.org/10.1155/2019/5126071.
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Understanding the grafting behavior of the aryldiazonium cations is of fundamental and also of practical importance for the vast number of applications that involve the use of modified graphene oxide (from simple adsorption process to electronic and photovoltaic applications). In this work, the mechanism of the adsorption and grafting of diazonium cations on the graphene oxide surface was investigated by the use of density functional theory. Two types of aryldiazonium cations, one bearing only phenyl ring and the other nitrophenyl, were selected as adsorbates/grafted moiety. By evaluating the adsorption energies at 7 different positions onto the graphene oxide both in the gaseous and solvent phase (using COSMO approach), the most probable adsorption sites were found. Moreover, the most stable adsorption sites were used to calculate and plot NCI (noncovalent interactions). The obtained results are important as they not only give molecular insights regarding the nature of the interaction and its dependence on the adsorption site of the graphene oxide surface but also on the activation energy for such a grafting reaction to take place, providing a mechanistic aspect to understand these grafting reactions.
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Ismagambetov, Olzhas, Nakhypbek Aldiyarov, Nurlan Almas, et al. "Atomistic Modeling of Natural Gas Desulfurization Process Using Task-Specific Deep Eutectic Solvents Supported by Graphene Oxide." Molecules 29, no. 22 (2024): 5282. http://dx.doi.org/10.3390/molecules29225282.
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This study employs Density Functional Theory (DFT) calculations and traditional all-atom Molecular Dynamics (MD) simulations to reveal atomistic insights into a task-specific Deep Eutectic Solvent (DES) supported by graphene oxide with the aim of mimicking its application in the natural gas desulfurization process. The DES, composed of N,N,N′,N′-tetramthyl-1,6-hexane diamine acetate (TMHDAAc) and methyldiethanolamine (MDEA) supported by graphene oxide, demonstrates improved efficiency in removing hydrogen sulfide from methane. Optimized structure and HOMO-LUMO orbital analyses reveal the distinct spatial arrangements and interactions between hydrogen sulfide, methane, and DES components, highlighting the efficacy of the DES in facilitating the separation of hydrogen sulfide from methane through DFT calculations. The radial distribution function (RDF) and interaction energies, as determined by traditional all-atom MD simulations, provide insights into the specificity and strength of the interactions between the DES components supported by graphene oxide and hydrogen sulfide. Importantly, the stability of the DES structure supported by graphene oxide is maintained after mixing with the fuel, ensuring its robustness and suitability for prolonged desulfurization processes, as evidenced by traditional all-atom MD simulation results. These findings offer crucial insights into the molecular-level mechanisms underlying the desulfurization of natural gas, guiding the design and optimization of task-specific DESs supported by graphene oxide for sustainable and efficient natural gas purification.
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Czajka, Michael, Robert A. Shanks, and Ing Kong. "Preparation of graphene and inclusion in composites with poly(styrene-b-butadiene-b-styrene)." Science and Engineering of Composite Materials 22, no. 1 (2015): 7–16. http://dx.doi.org/10.1515/secm-2013-0119.
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AbstractThe aim of this work was to prepare and characterize nanocomposites containing graphene from intercalated graphite. The graphene was produced by rapid thermal expansion using expandable graphite oxide or obtained commercially. The polymer used was poly(styrene-b-butadiene-b-styrene) (SBS). The SBS was dissolved in p-xylene and the graphene was ultrasonically suspended in the xylene solution. The morphology, dynamic mechanical, electrical, and thermal properties of composites were characterized. Graphene at 1% (w/w) (hydrogen atmosphere) was found to increase the storage modulus (68%) and loss modulus (147%) of the glassy state of polybutadiene in SBS. The damping factor of SBS was enhanced by 74% corresponding to the polystyrene phase of SBS using Cheap Tubes graphene. The composites were insulators at 1% (w/w). The styrene groups in SBS strongly adsorb onto the graphenes, preventing a percolation network that would enhance electrical permittivity. Graphene enhanced physical crosslinks of the polystyrene phase to increase the modulus at low concentration. Graphene dispersion using ultrasonic shear depended on π-π interactions between the aromatic rings of the solvent, graphene, and polystyrene. This is a simple, fast, cheap, and scalable way of making high-quality graphene and a new way of graphene dispersal in polymers.
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Arunachalam, Vaishali, and Sukumaran Vasudevan. "Graphene–Solvent Interactions in Nonaqueous Dispersions: 2D ROESY NMR Measurements and Molecular Dynamics Simulations." Journal of Physical Chemistry C 122, no. 3 (2018): 1881–88. http://dx.doi.org/10.1021/acs.jpcc.7b11138.
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Moni, Grace, Jiji Abraham, Chinchu Kurian, Ayarin Joseph, and Soney C. George. "Effect of reduced graphene oxide on the solvent transport characteristics and sorption kinetics of fluoroelastomer nanocomposites." Physical Chemistry Chemical Physics 20, no. 26 (2018): 17909–17. http://dx.doi.org/10.1039/c8cp02411a.
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Molecular transport characteristics of fluoroelastomer nanocomposites in aromatic hydrocarbons exhibited improved chemical resistivity by the incorporation of reduced graphene oxide, due to its better reinforcing efficiency and improved polymer-filler interactions.
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Son, Chang Yun, and Zhen-Gang Wang. "Image-charge effects on ion adsorption near aqueous interfaces." Proceedings of the National Academy of Sciences 118, no. 19 (2021): e2020615118. http://dx.doi.org/10.1073/pnas.2020615118.
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Electrostatic interactions near surfaces and interfaces are ubiquitous in many fields of science. Continuum electrostatics predicts that ions will be attracted to conducting electrodes but repelled by surfaces with lower dielectric constant than the solvent. However, several recent studies found that certain “chaotropic” ions have similar adsorption behavior at air/water and graphene/water interfaces. Here we systematically study the effect of polarization of the surface, the solvent, and solutes on the adsorption of ions onto the electrode surfaces using molecular dynamics simulation. An efficient method is developed to treat an electrolyte system between two parallel conducting surfaces by exploiting the mirror-expanded symmetry of the exact image-charge solution. With neutral surfaces, the image interactions induced by the solvent dipoles and ions largely cancel each other, resulting in no significant net differences in the ion adsorption profile regardless of the surface polarity. Under an external electric field, the adsorption of ions is strongly affected by the surface polarization, such that the charge separation across the electrolyte and the capacitance of the cell is greatly enhanced with a conducting surface over a low-dielectric-constant surface. While the extent of ion adsorption is highly dependent on the electrolyte model (the polarizability of solvent and solutes, as well as the van der Waals radii), we find the effect of surface polarization on ion adsorption is consistent throughout different electrolyte models.
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LU, Yuxuan, Fang-Min Lin, Wei-Yu Long, and Chih-Ting Lin. "Impact of Water-Water Correlation at Suspended Graphene/Water Interface Under Different Electro-Modulated." ECS Meeting Abstracts MA2024-01, no. 33 (2024): 1630. http://dx.doi.org/10.1149/ma2024-01331630mtgabs.
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Graphene-based devices have extensive applications in aqueous environments. The molecular interactions across the graphene sheet significantly impact various devices, although few researches focused on elucidating the interface effects. In this study, we utilize trench structure to make graphene unilaterally and bilaterally suspended in water. The conduction status of both lateral and longitudinal currents (Id, Is, Ig) of graphene was monitored under two suspension scenarios to investigate the changes in interface evolution with the introduction of solvent-solvent interactions. For unilaterally suspended graphene, the current perpendicular to the graphene channel direction remains in the off state. For bilaterally suspended graphene, the current path is formed vertically between the graphene channel and the gate electrode, perpendicular to the direction of the graphene. This experimental setup illustrates the possibilities for exploring interfacial characteristics at the interface between 2D materials and solutions through practical experimentation. The detailed fabrication process of the graphene field-effect-transistor (GFET) device is depicted in Fig. 1. To fabricate the microchannel structure, a microfluidic pattern was generated through photolithography on the SiO2/Si substrate spun with a layer of photoresist. Then, the corresponding microchannel pattern with a thickness of 300 nm SiO2 and 30 μm Si layer was etched by reactive-ion etching (RIE) to form a trench capable of storing water. Afterward, Au electrodes were placed next to the microfluidic channel via evaporation utilizing a shadow mask. The second critical step involves the preparation of graphene. Graphene sheets were grown on a copper foil through the chemical vapor deposition (CVD) method. With the support of PMMA film, physically stacked graphene bilayer graphene was transferred to the target substrate. Ultimately, the suspended bilayer graphene was submerged in acetone for 24 hours to remove the PMMA layer and immersed in isopropanol (IPA) and DI water to clean the residues. According to this device structure, we successfully fabricate the suspension of graphene unilaterally or bilaterally in water. When introducing water through the trench, the bottom surface of the suspended graphene contacts with water molecules, while the upper surface of the suspended graphene is exposed to air. This configuration leads to a unilateral suspension in water (unilateral-suspension GFET). Conversely, when water is introduced through the trench and water is also added above the graphene channel, graphene comes into contact with water on both sides. This configuration results in its bilateral suspension in the water (bilateral-suspension GFET). The electronic transport characteristics of unilateral-suspension GFET and bilateral-suspension GFET were measured by Agilent semiconductor analysis B1500A. The gate voltage was applied to water through an Ag/AgCl electrode. Fig. 2 (a) displays the Raman spectroscopy of suspended graphene on GFET device. The most notable features of the Raman spectrum are the G peak around 1580 cm-1, and the 2D band around 2700 cm-1, which are typical characteristics of graphene. The ID/IG ratio of 0.19 indicates the good quality of the graphene layers. As shown in Fig. 2 (b), the scanning electron microscope (SEM) result of suspended graphene on the GFET device verifies the presence of large-area graphene. The diagram displays a clear demarcation line, facilitating the identification of graphene presence on the substrate. This can also imply the excellent quality of graphene with few defects. The transport behavior of unilateral-suspension GFET and bilateral-suspension GFET are measured individually, as shown in Fig. 3. The sum (ΔI) of The drain current behavior (Id) and source current behavior (Is), and gate current behavior (Ig) are recorded with changed gate voltages (from -1V to +1V) and constant VDS (VDS= 0.1V). For unilateral-suspension GFET, ΔI and Ig keep constant at zero, and there is no conduction path perpendicular to the graphene channel direction. For bilateral-suspension GFET, ΔI and Ig at positive gate voltage are opposite in direction and equal in absolute value, this indicates the formation of an obvious path between the channel and gate electrode. The apparent interfacial evolution is believed to change with the introduction of the other side of water. In conclusion, we compare the electrical characteristics shown by two different suspension situations of graphene-based field effect transistors. There are some interesting results of the conduction path relating to interfacial evolution. This result has potential for chemical sensing or battery application. Furthermore, it can contribute to fundamental research about the interface interaction between suspended graphene and water. Figure 1
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Ramezani, Ghazaleh, Theo G. M. van de Ven, and Ion Stiharu. "Novel In-Situ Synthesis Techniques for Cellulose-Graphene Hybrids: Enhancing Electrical Conductivity for Energy Storage Applications." Recent Progress in Materials 07, no. 01 (2025): 1–50. https://doi.org/10.21926/rpm.2501004.
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This study investigates the hypothesis that diverse synthesis techniques can yield cellulose-graphene hybrids with tailored properties for specific applications, enabling advancements in flexible electronics, energy storage, environmental remediation, and biomedical devices. We examined and compared multiple synthesis methods, including chemical reduction, in-situ synthesis, green synthesis using natural reducing agents, solvent-assisted approaches, hydrothermal and solvothermal techniques, mechanical and chemical treatments, and electrochemical exfoliation. Each method was assessed for its impact on material properties, scalability, and environmental footprint. Chemical reduction and in-situ synthesis resulted in uniform graphene dispersion and superior electrical conductivity, with the I(D)/I(G) ratio in Raman spectra indicating successful reduction of graphene oxide (GO) to reduced graphene oxide (rGO). Green synthesis, particularly using cow urine as a reducing agent, provided an eco-friendly alternative, leveraging its natural constituents to reduce GO to rGO while minimizing environmental impact. Mechanical and chemical treatments effectively prepared cellulose microfibers for compatibility with graphene, enhancing interfacial interactions and stress transfer in the resulting composites. Solvent-assisted techniques allowed precise tuning of composite properties through the selection of appropriate solvents and processing conditions. Hydrothermal and solvothermal methods produced hybrids with high purity and uniformity under high-temperature and high-pressure conditions, facilitating the reduction of GO to rGO and promoting strong bonding between cellulose and graphene. Electrochemical exfoliation generated high-quality graphene with controlled characteristics, allowing it to produce graphene with fewer defects compared to other methods. Findings reveal that cellulose-graphene hybrids synthesized using these methods exhibit significant improvements in thermal stability, electrical conductivity, and mechanical strength. For instance, even low rGO additions (3 wt%) surpassed the percolation threshold, resulting in electrical conductivity of 1.9 × 10<sup>-5</sup> S cm<sup>-1</sup> for cellulose/rGO (8 wt%) aerogels. These enhanced properties underscore the importance of carefully selecting synthesis techniques to optimize material characteristics for target applications. The research provides a comprehensive understanding of synthesis-method-property relationships, offering valuable insights for the development of advanced cellulose-graphene hybrid materials and highlighting their transformative potential across various high-impact fields, including flexible electronics, energy storage devices, environmental remediation systems, and biomedical applications.
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Borzehandani, Mostafa Yousefzadeh, Emilia Abdulmalek, Mohd Basyaruddin Abdul Rahman, and Muhammad Alif Mohammad Latif. "Elucidating the Aromatic Properties of Covalent Organic Frameworks Surface for Enhanced Polar Solvent Adsorption." Polymers 13, no. 11 (2021): 1861. http://dx.doi.org/10.3390/polym13111861.
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Covalent organic frameworks (COFs) have a distinguished surface as they are mostly made by boron, carbon, nitrogen and oxygen. Many applications of COFs rely on polarity, size, charge, stability and hydrophobicity/hydrophilicity of their surface. In this study, two frequently used COFs sheets, COF-1 and covalent triazine-based frameworks (CTF-1), are studied. In addition, a theoretical porous graphene (TPG) was included for comparison purposes. The three solid sheets were investigated for aromaticity and stability using quantum mechanics calculations and their ability for water and ethanol adsorption using molecular dynamics simulations. COF-1 demonstrated the poorest aromatic character due to the highest energy delocalization interaction between B–O bonding orbital of sigma type and unfilled valence-shell nonbonding of boron. CTF-1 was identified as the least kinetically stable and the most chemically reactive. Both COF-1 and CTF-1 showed good surface properties for selective adsorption of water via hydrogen bonding and electrostatic interactions. Among the three sheets, TPG’s surface was mostly affected by aromatic currents and localized π electrons on the phenyl rings which in turn made it the best platform for selective adsorption of ethanol via van der Waals interactions. These results can serve as guidelines for future studies on solvent adsorption for COFs materials.
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González, Munduate Kizkitza, Arocena Izaskun Larraza, Alberdi Loli Martin, Arantxa Eceiza, and Nagore Gabilondo. "Effective reinforcement of plasticized starch by the incorporation of graphene, graphene oxide and reduced graphene oxide." International Journal of Biological Macromolecules 249 (August 3, 2023): 126130. https://doi.org/10.1016/j.ijbiomac.2023.126130.
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Plasticized starch (PLS) nanocomposite films using glycerol and reinforced with graphene (G) and graphene oxide (GO) were prepared by solvent casting procedure. On one hand, the influence of adding different G contents into the PLS matrix was analyzed. In order to improve the stability of G nanoflakes in water, Salvia extracts were added as surfactants. The resulting nanocomposites presented improved mechanical properties. A maximum increase of 287 % in Young's modulus and 57 % in tensile strength was achieved for nanocomposites with 5 wt% of G. However, it seemed that Salvia acted as co-plasticizer for the PLS. Moreover, the addition of the highest G content led to an improvement of the electrical conductivity close to 5 × 10 6 S/m compared to the matrix. On the other hand, GO was also incorporated as nanofiller to prepare nanocomposites. Thus, the effect of increasing the GO content in the final behavior of the PLS nanocomposites was evaluated. The characterization of GO containing PLS nanocomposites showed that strong starch/GO interactions and a good dispersion of the nanofiller were achieved. Moreover, the acidic treatment applied for the reduction of the GO was found to be effective, since the electrical conductivity was 150 times bigger than its G containing counterpart.
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Araya-Hermosilla, Esteban, Matteo Minichino, Virgilio Mattoli, and Andrea Pucci. "Chemical and Temperature Sensors Based on Functionalized Reduced Graphene Oxide." Chemosensors 8, no. 2 (2020): 43. http://dx.doi.org/10.3390/chemosensors8020043.
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In this work, we investigated the functionalization of reduced graphene oxide (rGO) with 2-(dodecen-1-yl) succinic anhydride (TPSA) to increase the rGO effective interactions with organic solvents both in liquid and vapor phases. Thermogravimetric analysis, STEM, XPS, FTIR-ATR, and Raman spectroscopy confirmed the effective functionalization of rGO with about the 30 wt% of grafted TPSA without affecting the structural characteristics of graphene but successfully enhancing its dispersibility in the selected solvent except for the apolar hexane. Solid TPSA-rGO dispersions displayed a reproducible semiconducting (activated) electrical transport with decreased resistance when heated from 20 °C to 60 °C and with a negative temperature coefficient of 10−3 K−1, i.e., comparable in absolute value with temperature coefficient in metals. It is worth noting that the same solid dispersions showed electrical resistance variation upon exposure to vapors with a detection limit in the order of 10 ppm and sensitivity α of about 10−4 ppm−1.
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Mohammadsalih, Zaid G., Beverley J. Inkson, and Biqiong Chen. "Structure and Properties of Polystyrene-Co-Acrylonitrile/Graphene Oxide Nanocomposites." Journal of Composites Science 7, no. 6 (2023): 225. http://dx.doi.org/10.3390/jcs7060225.
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Polymer/graphene nanocomposites have attracted significant attention from the research community over the past two decades. In this work, nanocomposites of polystyrene-co-acrylonitrile (SAN) and graphene oxide (GO) were prepared using a solution blending method with tetrahydrofuran as the solvent. The GO loadings used were 0.1, 0.25, 0.5, and 1.0 wt.%. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy were employed to characterize the structure and morphology of SAN/GO nanocomposites. Thermal analysis showed increases in the glass transition (Tg) and peak thermal degradation (Tdpeak) temperatures of SAN by the additions of GO, with Tg increasing by 3.6 °C and Tdpeak by 19 °C for 1.0 wt.% GO loading. Dynamic mechanical analysis revealed that the storage modulus of SAN was also enhanced with the incorporations of GO by up to 62% for 1.0 wt.% loading. These property enhancements may be attributed to a good dispersion of GO in the polymer matrix and their interfacial interactions.
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Zhu, Jing, Binglin Lu, Shanshan Liu, et al. "Magnetic Graphene Dispersive Solid-Phase Extraction for the Determination of Phthalic Acid Esters in Flavoring Essences by Gas Chromatography Tandem Mass Spectrometry." Journal of Chromatographic Science 58, no. 8 (2020): 770–78. http://dx.doi.org/10.1093/chromsci/bmaa032.
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Abstract In the present study, a sensitive, efficient and repeatable method for the simultaneous extraction and determination of 13 types of phthalic acid esters (PAEs) in flavoring essence samples using magnetic graphene solid-phase extraction coupled with gas chromatography tandem mass spectrometry was developed. Due to the unique structure of magnetic graphene, it has several advantages, such as large surface area and fast separation ability. This unique structure not only provided strong magnetic responsiveness for the separation but also prevented the self-aggregation of graphene. The large delocalized p-electron system of graphene can form strong π-stacking interactions with the benzene ring. Thus, graphene may be also a good candidate adsorbent for the adsorption of benzenoid-form compounds. Several magnetic soild-phase extraction parameters, such as elution solvents, amounts of sorbents, enrichment time and desorption time were optimized. The optimized procedures for this method were performed by ultrasonication using ethyl acetate as elution solvent for 5 min. Under the optimal conditions, the developed method provided spiked recoveries of 75.0–105.3% with relative standard deviations of ~5.6% and limits of detection were 0.011–0.091 mg/kg. Good linear relationships were observed with the coefficient of determination (R2) &gt; 0.993 for all the analytes. Finally, the validated method was successfully applied to the analysis of PAEs in real samples.
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Yu, Li, Fei Ma, Liangxiao Zhang, and Peiwu Li. "Determination of Aflatoxin B1 and B2 in Vegetable Oils Using Fe3O4/rGO Magnetic Solid Phase Extraction Coupled with High-Performance Liquid Chromatography Fluorescence with Post-Column Photochemical Derivatization." Toxins 11, no. 11 (2019): 621. http://dx.doi.org/10.3390/toxins11110621.
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In this study, magnetic graphene nanocomposite Fe3O4/rGO was synthesized by facile one-pot solvothermal method. The nanocomposite was successfully used as magnetic solid phase extraction (MSPE) adsorbents for the determination of aflatoxins in edible vegetable oils through the π–π stacking interactions. MSPE parameters including the amount of adsorbents, extraction and desorption time, washing conditions, and the type and volume of desorption solvent were optimized. Under optimal conditions, good linear relationships were achieved. Limits of detection of this method were as low as 0.02 µg/kg and 0.01 µg/kg for aflatoxin B1 and B2, respectively. Finally, the magnetic graphene nanocomposite was successfully applied to aflatoxin analysis in vegetable oils. The results indicated that the recoveries of the B-group aflatoxins ranged from 80.4% to 106.0%, whereas the relative standard deviations (RSDs) were less than 8.1%. Owing to the simplicity, rapidity and efficiency, Fe3O4/rGO magnetic solid phase extraction coupled with high-performance liquid chromatography fluorescence with post-column photochemical derivatization (Fe3O4/rGO MSPE-HPLC-PCD-FLD) is a promising analytical method for routine and accurate determination of aflatoxins in lipid matrices.
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Sohail, Uroosa, Faizan Ullah, Nur Hazimah Binti Zainal Arfan, et al. "Transition Metal Sensing with Nitrogenated Holey Graphene: A First-Principles Investigation." Molecules 28, no. 10 (2023): 4060. http://dx.doi.org/10.3390/molecules28104060.
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The toxicity of transition metals, including copper(II), manganese(II), iron(II), zinc(II), hexavalent chromium, and cobalt(II), at elevated concentrations presents a significant threat to living organisms. Thus, the development of efficient sensors capable of detecting these metals is of utmost importance. This study explores the utilization of two-dimensional nitrogenated holey graphene (C2N) nanosheet as a sensor for toxic transition metals. The C2N nanosheet’s periodic shape and standard pore size render it well suited for adsorbing transition metals. The interaction energies between transition metals and C2N nanosheets were calculated in both gas and solvent phases and were found to primarily result from physisorption, except for manganese and iron which exhibited chemisorption. To assess the interactions, we employed NCI, SAPT0, and QTAIM analyses, as well as FMO and NBO analysis, to examine the electronic properties of the TM@C2N system. Our results indicated that the adsorption of copper and chromium significantly reduced the HOMO–LUMO energy gap of C2N and significantly increased its electrical conductivity, confirming the high sensitivity of C2N towards copper and chromium. The sensitivity test further confirmed the superior sensitivity and selectivity of C2N towards copper. These findings offer valuable insight into the design and development of sensors for the detection of toxic transition metals.
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Mahendran, R., D. Sridharan, K. Santhakumar, and G. Gnanasekaran. "Green Route Fabrication of Graphene Oxide Reinforced Polymer Composites with Enhanced Mechanical Properties." Journal of Nanoscience 2016 (July 13, 2016): 1–8. http://dx.doi.org/10.1155/2016/6410295.
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A facile and “Green” route has been applied to fabricate graphene oxide (GO) reinforced polymer composites utilizing “deionized water” as solvent. The GO was reinforced into water soluble poly(vinyl alcohol) (PVA) and poly-2-acrylamido-2-methyl-1-propanesulfonic acid (PAMPS) matrix by ultrasonication followed by mechanical stirring. The incorporation and dispersion of the GO in the polymer matrix were analyzed by XRD, FE-SEM, AFM, FT-IR, and TGA. Further, the FE-SEM and AFM images revealed that the surface roughness and agglomeration of the GO in the polymer matrix increased by increasing its concentration. Ionic exchange capacity, proton conductivity, and tensile texture results showed that the reinforcement of GO in the polymer matrix enhances the physicochemical properties of the host polymer. These PVA/PAMPS/GO nanocomposites showed improved mechanical stability compared to the pristine polymer, because of strong interfacial interactions within the components and homogeneous dispersion of the GO sheets in the PVA/PAMPS matrix.
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Mohamad, Sharifah, Shabnam Bakhshaei, Ninie Suhana Abdul Manan, N. A. Parmin, and Siti Khalijah Mahmad Rozi. "Free Fatty Acid from Waste Palm Oil Functionalized Magnetic Nanoparticles Immobilized on Surface Graphene Oxide as a New Adsorbent for Simultaneously Detecting Hazardous Polycyclic Aromatic Hydrocarbons and Phthalate Esters in Food Extracts." Journal of Nanoscience and Nanotechnology 21, no. 11 (2021): 5522–34. http://dx.doi.org/10.1166/jnn.2021.19454.
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A newly synthesized free fatty acids from waste palm oil functionalized magnetic nanoparticles immobilized on the surface of graphene oxide (FFA@MNP-GO) was successfully synthesized and characterized in this research. The combinations of long alkyl chain of free fatty acid with graphene oxide that consists of large delocalized 77-electron systems and abundant of hydrophilic groups with hydroxyl, epoxide and carboxylic groups offer the determination of simultaneous wide range of polarities of organic pollutants in real matrices through hydrogen bonding, hydrophobic and 77-77 interactions. The fabricated adsorbent was successfully applied as a magnetic solid phase extraction (MSPE) adsorbent for the simultaneous separation of selected phthalate esters (PAEs) and polycyclic aromatic hydrocarbons (PAHs) in apple and cabbage extracts prior to their high performance liquid chromatography with diode-array detector (HPLC-DAD) determination. Factors affecting the extraction efficiency such as amount of adsorbent, desorption solvent, volume of desorption solvent, extraction time, desorption time, pH and sample volume were investigated and optimized. The results revealed that under optimal conditions, the detection limit of selected PAEs and PAHs were in the range of 0.56-0.97 ng mL-1 and 0.02–0.93 ng mL-1, respectively. The spiked recoveries of real apple and cabbage extracts for PAEs and PAHs were in the range of 81.5-117.6% with good relative standard deviation (RSD) (n = 5) less than 10% and 86.7-118.2% with acceptable RSDs (n = 5) ranging from 1.5 to 11.0%, respectively. This study reported for the first time the use of MSPE procedure for simultaneous determination of chosen PAHs and PAEs in real samples including apple and cabbage extracts by using new adsorbent, FFA@MNP-GO.
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Li, Shuxuan, Can Li, Baowei Su, Michael Z. Hu, Xueli Gao, and Congjie Gao. "Amino-functionalized graphene quantum dots (aGQDs)-embedded thin film nanocomposites for solvent resistant nanofiltration (SRNF) membranes based on covalence interactions." Journal of Membrane Science 588 (October 2019): 117212. http://dx.doi.org/10.1016/j.memsci.2019.117212.
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Shaik, Mohammed, Manawwer Alam, Syed Adil, et al. "Solvothermal Preparation and Electrochemical Characterization of Cubic ZrO2 Nanoparticles/Highly Reduced Graphene (HRG) based Nanocomposites." Materials 12, no. 5 (2019): 711. http://dx.doi.org/10.3390/ma12050711.
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A single-step solvothermal approach to prepare stabilized cubic zirconia (ZrO2) nanoparticles (NPs) and highly reduced graphene oxide (HRG) and ZrO2 nanocomposite (HRG@ZrO2) using benzyl alcohol as a solvent and stabilizing ligand is presented. The as-prepared ZrO2 NPs and the HRG@ZrO2 nanocomposite were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD), which confirmed the formation of ultra-small, cubic phase ZrO2 NPs with particle sizes of ~2 nm in both reactions. Slight variation of reaction conditions, including temperature and amount of benzyl alcohol, significantly affected the size of resulting NPs. The presence of benzyl alcohol as a stabilizing agent on the surface of ZrO2 NPs was confirmed using various techniques such as ultraviolet-visible (UV-vis), Fourier-transform infrared (FT-IR), Raman and XPS spectroscopies and thermogravimetric analysis (TGA). Furthermore, a comparative electrochemical study of both as-prepared ZrO2 NPs and the HRG@ZrO2 nanocomposites is reported. The HRG@ZrO2 nanocomposite confirms electronic interactions between ZrO2 and HRG when compared their electrochemical studies with pure ZrO2 and HRG using cyclic voltammetry (CV).
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Ferguson, Andrew J., and Jeff Blackburn. "(Invited) The Role of Counterion Chemistry on the Nature of Charge Carriers in Redox-Doped Nanocarbons." ECS Meeting Abstracts MA2024-02, no. 11 (2024): 1458. https://doi.org/10.1149/ma2024-02111458mtgabs.
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The performance of many emerging electronic and optoelectronic devices based on organic and nanoscale carbon semiconductors can be fine-tuned by control of the charge carrier density injected by redox dopants. We have recently demonstrated that the chemical structure (size, shape, and redox properties) of the dopant counterion has a significant influence on the electrostatic interactions with the charge carrier, which affects charge (de)localization and transport. We have exploited this to enhance the thermoelectric properties of thin film networks of single-walled carbon nanotubes (SWCNTs) and have observed strong modulation of the complex dielectric properties of isolated SWCNTs dispersed in a low dielectric solvent. Here we extend these studies to the redox doping of graphene nanoribbons (GNRs). We once again show that the chemical structure of the dopant counterion has a critical influence on the properties of the injected charge carriers. Large, spherical dopant counterions based on bulky benzyloxy-substituted icosahedral dodecaborane cluster dopants, DDBs, lead to enhanced delocalization of charge carriers and transport, as observed by UV-Vis-NIR / Fourier Transform Infrared (FTIR) spectroscopy and microwave conductivity, respectively. In contrast, the increased electrostatic interactions with the planar dopant counterion 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) results in stronger carrier localization, inhibiting transport. We will provide a comparison of the doping of GNRs, with SWCNTs and conjugated polymers.
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Díez-Pascual, Ana M. "Effect of Graphene Oxide on the Properties of Poly(3-Hydroxybutyrate-co-3-Hydroxyhexanoate)." Polymers 13, no. 14 (2021): 2233. http://dx.doi.org/10.3390/polym13142233.
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The main shortcomings of polyhydroxybutyrate (PHB), which is a biodegradable and biocompatible polymer used for biomedical and food packaging applications, are its low thermal stability, poor impact resistance and lack of antibacterial activity. This issue can be improved by blending with other biodegradable polymers such as polyhydroxyhexanoate to form poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), which is a copolymer with better impact strength and lower melting point. However, PHBHHx shows reduced stiffness than PHB and poorer barrier properties against moisture and gases, which is a drawback for use in the food industry. In this regard, novel biodegradable PHBHHx/graphene oxide (GO) nanocomposites have been prepared via a simple, cheap and environmentally friendly solvent casting method to enhance the mechanical properties and antimicrobial activity. The morphology, mechanical, thermal, barrier and antibacterial properties of the nanocomposites were assessed via several characterization methods to show the enhancement in the biopolymer properties. The stiffness and strength of the biopolymer were enhanced up to 40% and 28%, respectively, related to the strong matrix-nanofiller interfacial adhesion attained via hydrogen bonding interactions. Moreover, the nanocomposites showed superior thermal stability (as far as 40 °C), lower water uptake (up to 70%) and better gas and vapour barrier properties (about 45 and 35% reduction) than neat PHBHHx. They also displayed strong biocide action against Gram positive and Gram negative bacteria. These bio-based nanocomposites with antimicrobial activity offer new perspectives for the replacement of traditional petroleum-based synthetic polymers currently used for food packaging.
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Asha, Aysha Siddika, Benjoe Rey B. Visayas, Maricris L. Mayes, and Caiwei Shen. "Understanding the Effect of Trace Solvent Content on Properties of Polymer Electrolytes through Molecular Dynamics Simulations." ECS Meeting Abstracts MA2023-01, no. 4 (2023): 862. http://dx.doi.org/10.1149/ma2023-014862mtgabs.
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The rapid growth of mobile, portable, wearable and flexible electronics leads to the increasing demand for energy storage devices using solid-state polymer electrolytes (PEs), which outperform liquid electrolytes in terms of safety, mechanical properties, and simplicity of device fabrication and packaging. However, processing PEs will always introduce solvent molecules that greatly affect the ionic conductivity and mechanical properties. For example, PEs prepared through solution-casting methods always have solvent residues. A trace amount of water molecules absorbed from the air is also inevitable. Recently, we demonstrated the controlled introduction of solvent molecules to PEs to balance the ionic conductivity and mechanical stiffness for structural energy storage applications. To better understand how solvent molecules behave and interact with other components in PEs, here we present the molecular dynamics simulation of a representative polymer electrolyte system with various water content. We use simulation results to determine the effect of trace water content before forming a liquid phase on ionic conductivity and mechanical properties. The insights into the molecular interactions in the PE system will help us design and optimize Pes’ composition and processing for practical applications. The simulation model of polymer electrolyte is built with polyethylene oxide (PEO) and lithium perchlorate (LiClO4) with various water contents, in which the water molecule to lithium-ion ratio ranges from 0 to 3. The electrolyte with each water content is simulated between two graphene electrodes to determine its ionic conductivity. Uniaxial deformation has been performed on the electrolyte to obtain the mechanical properties. All simulations were performed using the molecular dynamics simulation code LAMMPS with the CHARMM force field. The results show that the ionic conductivity of the polymer electrolyte system increases significantly (up to one order of magnitude) with the increase of water content (up to 3 water molecules per lithium ion), even when the added water does not form a continuous liquid phase. The change of ionic conductivity with water content is correlated to the degree of association between different types of ions or molecules in the system, as evidenced by the evaluation of the radial distribution functions. As the association between polymer molecules and lithium ions reduces with increasing water, it becomes easier for the lithium ions to diffuse and resulting in higher ionic conductivity. It is also observed that the perchlorate ions’ interactions with polymer molecules remain the same with different water contents, which shows different roles of lithium ions and perchlorate ions in ion conduction in this system. On the other hand, the modulus of elasticity of the polymer electrolyte does not change much with the increase of water, which agrees with the previous experimental work of our group. This means that the trace amount of water is strongly associated with other solid molecules or ions and is not affecting the stiffness of the system as long as no liquid phase is formed. The results will lead to novel strategies to design polymer electrolytes with both high ionic conductivity and good mechanical properties for flexible or multifunctional energy storage applications.
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Mersal, Gaber A. M., I. S. Yahia та Hamdy S. El-Sheshtawy. "Lone pair Halogen (X2)…π Interactions Stabilizes Molecular Halogens (X2=I2, Br2, Cl2, and F2) on Reduced Graphene Oxide surface: Structural, Solvent Effect and optical properties". Journal of Molecular Structure 1244 (листопад 2021): 130963. http://dx.doi.org/10.1016/j.molstruc.2021.130963.
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Kiseleva, Svetlana G., Galina N. Bondarenko, Andrey V. Orlov, et al. "Hybrid Nanocomposites Based on Poly(3,6-dianiline-2,5-dichloro-1,4-benzoquinone): Synthesis, Structure and Properties." Polymers 16, no. 13 (2024): 1832. http://dx.doi.org/10.3390/polym16131832.
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Hybrid nanocomposites based on poly(3,6-dianiline-2,5-dichloro-1,4-benzoquinone) (PDACB) in salt form and graphene oxide (GO) have been obtained for the first time, and the significant influence of the preparation method on the composition and structure of nanocomposites and their functional properties has been demonstrated. Nanocomposites were prepared in three ways: via ultrasonic mixing of PDACB and GO; via in situ oxidative polymerization of 3,6-dianiline-2,5-dichloro-1,4-benzoquinone (DACB) in the presence of GO; and by heating a suspension of previously prepared PDACB and GO in DMF with the removal of the solvent. The results of the study of the composition, chemical structure, morphology, thermal stability and electrical properties of nanocomposites obtained via various methods are presented. Nanocomposites obtained by mixing the components in an ultrasonic field demonstrated strong intermolecular interactions between PDACB and GO both due to the formation of hydrogen bonds and π-stacking, as well as through electrostatic interactions. Under oxidative polymerization of DACB in the presence of GO, the latter participated in the oxidative process, being partially reduced. At the same time, a PDACB polymer film was formed on the surface of the GO. Prolonged heating for 4 h at 85 °C of a suspension of PDACB and GO in DMF led to the dedoping of PDACB with the transition of the polymer to the base non-conductive form and the reduction of GO. Regardless of the preparation method, all nanocomposites showed an increase in thermal stability compared to PDACB. All nanocomposites were characterized by a hopping mechanism of conductivity. Direct current (dc) conductivity σdc values varied within two orders of magnitude depending on the preparation conditions.
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Tsai, Hsin-Yen, Munusamy Sathish Kumar, Balaraman Vedhanarayanan, Hsin-Hui Shen, and Tsung-Wu Lin. "Urea-Based Deep Eutectic Solvent with Magnesium/Lithium Dual Ions as an Aqueous Electrolyte for High-Performance Battery-Supercapacitor Hybrid Devices." Batteries 9, no. 2 (2023): 69. http://dx.doi.org/10.3390/batteries9020069.
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A new deep eutectic solvent (DES) made from urea, magnesium chloride, lithium perchlorate and water has been developed as the electrolyte for battery-supercapacitor hybrid devices. The physicochemical characteristics of DES electrolytes and potential interactions between electrolyte components are well analyzed through electrochemical and spectroscopic techniques. It has been discovered that the properties of DES electrolytes are highly dependent on the component ratio, which allows us to engineer the electrolyte to meet the requirement of the battery application. Perylene tetracarboxylic di-imide and reduced graphene oxide ha ve been combined to produce a composite (PTCDI/rGO) that has been tested as the anode in DES electrolyte. This composite shows that the capacitive contribution is greater than 90% in a low scan rate, resulting in the high rate capability. The PTCDI/rGO electrode exhibits no sign of capacity degradation and its coulombic efficiency is close to 99% after 200 cycles, which suggests excellent reversibility and stability. On the other hand, the electrochemical performance of lithium manganese oxide as the cathode material is studied in DES electrolyte, which exhibits the maximum capacity of 76.5 mAh/g at 0.03 A/g current density. After being successfully examined in terms of electrode kinetics, capacity performance, and rate capability, the anode and cathode materials are combined to construct a two-electrode system with DES electrolyte. At a current density of 0.03 A/g, this system offers 43.5 mAh/g specific capacity and displays 55.5% retention of the maximum capacity at 1 A/g. Furthermore, an energy density of 53 Wh/kg is delivered at a power density of 35 W/kg.
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Manza, Hirasing T., Mangesh S. Dhore, and Shankar Amalraj. "2D Covalent Interaction of Aminophenol Functionalized Graphene Oxide." ECS Transactions 107, no. 1 (2022): 16531–37. http://dx.doi.org/10.1149/10701.16531ecst.
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The versatile applications of graphene oxide and its derivatives have attracted scientists to do keen research in the field of functionalized graphene oxide. Herein we report the synthesis of graphene oxide (GO) functionalized with 2,4-diaminophenol (2,4-DAP). This reaction is refluxing at 60oC for 18 hrs under the solvent of dimethylformamide (DMF). The graphene oxide is synthesized from graphite by modified hummer’s method. The developed product is subjected to X-ray diffraction spectroscopy (XRD) and infrared spectroscopy (IR). The results are revealing that the successful intercalation of amine group and GO to form GO-2,4-DAP product.
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Fernández-García, Jesús Manuel, and Nazario Martín. "(Invited) Corannulene-Based Molecular Nanographenes: Synthesis, Reduction, Supramolecular Complexation and Photophysical Properties." ECS Meeting Abstracts MA2023-01, no. 12 (2023): 1272. http://dx.doi.org/10.1149/ma2023-01121272mtgabs.
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The outstanding electronic properties of graphene-based materials make them one of the most promising assets for application in the electronics industry of the XXI century. Encouraged by these properties, a great number of materials scientists are currently engaged in the development of the emergent field of 2D materials. In the last decade, the reduction of the dimensionality to 1D (nanoribbons) and 0D (nanographenes NGs, or graphene quantum dots, GQDs) have become an important research topic by their singular properties. In this regard, the quantum confinement of the electrons and the edge effects of these graphene derived structures makes possible the bandgap opening and, therefore, the appearance of a semiconductor behavior. The bottom-up preparation of these new structures, specifically employing stepwise organic synthesis, lead to monodisperse molecular nanographenes with atomically controlled morphology and, therefore, to the control of photophysical properties at will. An example of this synthetic management is the insertion of non-hexagonal rings in the honeycomb pattern of NGs, endowing Gaussian curvature to these structures and making molecules with bowl or saddle shapes. Our research group has described the wet synthesis of curved corannulene-based nanographenes by a stepwise Sonogashira–[4+2]–Scholl strategy.[1] Using bromocorannulene 1 as starting material, and depending on the temperature and the oxidant agent used in the Scholl reaction, a [6]helicene corannulene-based nanographene 2 or a positively-negatively curved nanographene 3 were prepared. These molecular curved NGs present interesting photophysical properties such as thermal activated delayed fluorescence (TADF) or dual emission.[2] Additionally, the multi-electron acceptor nature of molecular NGs allows the reduction with alkali metals that normally remains hosted in the pockets of curved nanographenes leading to potential energy storage systems. Within a collaborative work, the reduction of nanographene 2 with Na metal has recently been performed.[3] The formation of a “naked” dianion C76H64 2– (2 2–) solvent separated from the two cationic moieties was observed affording unprecedented selectively reduced species. DFT calculations revealed significant changes in the electron density and the inversion of the ring current aromaticity. Finally, concave–convex interactions between curved nanographenes and fullerenes are known to lead to supramolecular complexes with special interest as photoinduced electron transfer systems, mimicking the photosynthetic process. In a collaborative work,[4] the supramolecular complexation of nanographene 3 with C60 was experimentally monitored by H NMR spectroscopy and studied by DFT calculations.The formation of complexes with stoichiometries 2:1, 1:1 and 1:2 is possible. Furthermore, when the complex was irradiated at 460nm, the formation of the C60 radical anion is observed in an amazing photoinduced electron transfer process. References 1 J. M Fernández-García, P. Evans, S. Medina Ribero, I. Fernández, D. García-Fresnadillo, J. Perles, J. Casado, N. Martín, J. Am. Chem. Soc. 2018, 140, 17188. 2 Manuscript in preparation. 3 Z. Zhou, Y, Zhu, J. M. Fernández-García, Z. Wei, I. Fernández, M. Petrukhina, N. Martín et al., Chem. Commun. 2022, 58, 5574. 4 S. Zank, J. M. Fernández-García, A. J. Stasyuk, A. A. Voityuk, M. Krug, M. Solà, D. Guldi and N. Martín, Angew. Chem. Int. Ed. 2022, 61, e202112834 Figure 1
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Kim, Ho Shin, Sabrina M. Huang, and Yaroslava G. Yingling. "Sequence dependent interaction of single stranded DNA with graphitic flakes: atomistic molecular dynamics simulations." MRS Advances 1, no. 25 (2016): 1883–89. http://dx.doi.org/10.1557/adv.2016.91.
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ABSTRACTIn an attempt to understand the structure and dynamics of ssDNA on graphene based surfaces, we performed all-atom implicit solvent molecular dynamics simulations of ssDNA on graphene and graphene oxide (GO) surfaces. Simulations indicate that adsorption of poly(A), poly(T) and poly (AT) have similar mechanisms of adsorption to free standing graphitic flakes, which are governed by a surface oxygen content. Specifically, higher oxygen content of a surface leads to decrease in persistence length of ssDNA. However, the role of DNA sequence on the physisorption mechanism is minimal.
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de Oliveira, Matheus Mendes, Sven Forsberg, Linnéa Selegård, and Danilo Justino Carastan. "The Influence of Sonication Processing Conditions on Electrical and Mechanical Properties of Single and Hybrid Epoxy Nanocomposites Filled with Carbon Nanoparticles." Polymers 13, no. 23 (2021): 4128. http://dx.doi.org/10.3390/polym13234128.
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Graphene nanoplatelets (GNP) and carbon nanotubes (CNT) are used to enhance electrical and mechanical properties of epoxy-based nanocomposites. Despite the evidence of synergetic effects in the hybrid GNP-CNT-epoxy system, there is still a lack of studies that focus on the influence of different dispersion methods on the final properties of these ternary systems. In the present work, direct and indirect ultrasonication methods were used to prepare single- and hybrid-filled GNP-CNT-epoxy nanocomposites, varying the amplitude and time of sonication in order to investigate their effect on electrical and thermomechanical properties. Impedance spectroscopy was combined with rheology and electron microscopy to show that high-power direct sonication tends to degrade electrical conductivity in GNP-CNT-epoxy nanocomposites due to damage caused in the nanoparticles. CNT-filled samples were mostly benefitted by low-power direct sonication, achieving an electrical conductivity of 1.3 × 10−3 S·m−1 at 0.25 wt.% loading, while indirect sonication was not able to properly disperse the CNTs and led to a conductivity of 1.6 ± 1.3 × 10−5. Conversely, specimens filled with 2.5 wt. % of GNP and processed by indirect sonication displayed an electrical conductivity that is up to 4 orders of magnitude higher than when processed by direct sonication, achieving 5.6 × 10−7 S·m−1. The introduction of GNP flakes improved the dispersion state and conductivity in hybrid specimens processed by indirect sonication, but at the same time impaired these properties for high-power direct sonication. It is argued that this contradictory effect is caused by a selective localization of shorter CNTs onto GNPs due to strong π-π interactions when direct sonication is used. Dynamic mechanical analysis showed that the addition of nanofillers improved epoxy’s storage modulus by up to 84%, but this property is mostly insensitive to the different processing parameters. Decrease in crosslinking degree and presence of residual solvent confirmed by Fourier-transform infrared spectroscopy, however, diminished the glass transition temperature of the nanocomposites by up to 40% when compared to the neat resin due to plasticization effects.
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Oh, Yuna, Hoi Kil Choi, Hana Jung, et al. "Analysis of the effect of organic solvent–sheet interfacial interaction on the exfoliation of sulfur-doped reduced graphene oxide sheets in a solvent system using molecular dynamics simulations." Physical Chemistry Chemical Physics 22, no. 36 (2020): 20665–72. http://dx.doi.org/10.1039/d0cp03498c.
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In this study, the effect of interfacial interaction between solvent and sheets on the exfoliation of sulfur-doped reduced graphene oxide (SrGO) sheets was studied, using molecular dynamics simulations.
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Kadhim, Ishraq Abd Ulrazzaq. "Biocompatibility of Alginate -Graphene Oxide Film for Tissue Engineering Applications." Key Engineering Materials 900 (September 20, 2021): 26–33. http://dx.doi.org/10.4028/www.scientific.net/kem.900.26.
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The present paper indicates promising potential of Sodium Alginate) Alg)/Graphene oxide (Go) films in fields bone tissue engineering (TE). The Sodium Alginate (Alg)/Graphene oxide (Go) films, were fabricated via (solvent casting method). The interaction of Sodium Alginate (Alg) with Graphene oxide (Go) via hydrogen bonding was confirmed by FTIR analysis. The swelling degree of Sodium Alginate (Alg)/Graphene oxid (Go) films was also studied. Furthermore, the biocompatibility of Sodium Alginate (Alg)/Graphene oxide (Go) films disclosed its non-cytotoxic effect on the cell lines (MG-63) in-vitro test, the viability of cell lines on the films, and hence its appropriateness as potent biomaterial for tissue engineering.
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Neklyudov, Vadim V., Nail R. Khafizov, Igor A. Sedov, and Ayrat M. Dimiev. "New insights into the solubility of graphene oxide in water and alcohols." Physical Chemistry Chemical Physics 19, no. 26 (2017): 17000–17008. http://dx.doi.org/10.1039/c7cp02303k.
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Here we demonstrate that the solubility of GO, and the stability of as-formed solutions depend not just on the solute and solvent cohesion parameters, as commonly believed, but mostly on the chemical interactions at the GO/solvent interface.
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Sahu, Sumit Ranjan, Mayanglambam Manolata Devi, Puspal Mukherjee, Pratik Sen, and Krishanu Biswas. "Optical Property Characterization of Novel Graphene-X (X=Ag, Au and Cu) Nanoparticle Hybrids." Journal of Nanomaterials 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/232409.
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The present investigation reports new results on optical properties of graphene-metal nanocomposites. These composites were prepared by a solution-based chemical approach. Graphene has been prepared by thermal reduction of graphene oxide (GO) at 90°C by hydrazine hydrate in an ammoniacal medium. This ammoniacal solution acts as a solvent as well as a basic medium where agglomeration of graphene can be prevented. This graphene solution has further been used for functionalization with Ag, Au, and Cu nanoparticles (NPs). The samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, UV-Vis spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to reveal the nature and type of interaction of metal nanoparticles with graphene. The results indicate distinct shift of graphene bands both in Raman and UV-Vis spectroscopies due to the presence of the metal nanoparticles. Raman spectroscopic analysis indicates blue shift of D and G bands in Raman spectra of graphene due to the presence of metal nanoparticles except for the G band of Cu-G, which undergoes red shift, reflecting the charge transfer interaction between graphene sheets and metal nanoparticles. UV-Vis spectroscopic analysis also indicates blue shift of graphene absorption peak in the hybrids. The plasmon peak position undergoes blue shift in Ag-G, whereas red shift is observed in Au-G and Cu-G.
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Liu, Ruoyu, Sirui Wang, Yuting Guo, Sheng-Feng Huang, and Takashi Tokumasu. "Coarse-Grained Molecular Dynamics Simulation of Ionomer-Mediated Carbon Cluster Bonding in Polymer Electrolyte Fuel Cell Catalyst Layers." ECS Meeting Abstracts MA2024-02, no. 43 (2024): 2902. https://doi.org/10.1149/ma2024-02432902mtgabs.
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In the field of sustainable energy technologies, Polymer Electrolyte Fuel Cells (PEFCs) represent a crucial advancement for achieving high-efficiency power generation. This study focuses on the specific behavior of ionomers within PEFCs, particularly how they facilitate the bonding of carbon clusters during the evaporation process, critical for the structural integrity and functionality of the catalyst layer. Amid the global shift toward a hydrogen economy, the development of robust and efficient PEFC technologies is imperative. The Nafion membrane, developed by DuPont, is the standard bearer for proton exchange membranes due to its superior proton conductivity, chemical stability, and durability. Despite these advantages, the performance of PEFCs under high temperature and low humidity conditions remains a challenge due to the reduced efficiency of proton transport. This research concentrates on the micro-mechanics of how ionomers assist in the bonding between carbon clusters during the drying stages of film formation, aiming to overcome this efficiency bottleneck. Employing Coarse-Grained Molecular Dynamics (CGMD) simulations, our study delves into the detailed interactions between ionomers and Pt-carbon clusters during evaporating solvents. The simulations use a refined computational model to capture the dynamic interplay during evaporation conceptualized as micro-differentiated boxes within the system as illustrated in Figure 1. These boxes allow for the analysis of ionomer behavior on a flat, graphene-sheet-modeled cluster surface adorned with Pt particles, assessing how different configurations influence structural and transport properties. This approach not only elucidates the role of ionomers in promoting the aggregation of carbon clusters during evaporation but also provides insight into the nuanced processes that govern the formation and stability of the catalyst layer. Initial simulations pointed out the need for adjustments in the force field settings, which were subsequently optimized to enhance the accuracy of the observations regarding ionomer distribution and bonding effectiveness during evaporation. With the foundational simulations set, future work will extend to exploring how various experimental conditions—such as solvent composition, and the size and density of platinum particles—affect ionomer bonding between carbon clusters. By adjusting these parameters systematically, we aim to define the optimal conditions that enhance the structural cohesion and functional performance of the catalyst layer. This investigation is expected to yield significant insights into the fundamental interactions and mechanisms at play in the bonding process, contributing to a deeper understanding of PEFC technology and leading to advancements in the production methods of these fuel cells. Ultimately, this research will help to refine and optimize the procedures for manufacturing more efficient and durable PEFCs, marking a substantial step toward more sustainable energy systems. Acknowledgment The New Energy and Industrial Technology Development Organization (NEDO) of Japan supported this work under Grant number NP20003. A part of the results was obtained by supercomputer system of Institute of Fluid Science, Tohoku University. Figure 1
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Ivaništšev, Vladislav, Trinidad Méndez-Morales, Ruth M. Lynden-Bell, et al. "Molecular origin of high free energy barriers for alkali metal ion transfer through ionic liquid–graphene electrode interfaces." Physical Chemistry Chemical Physics 18, no. 2 (2016): 1302–10. http://dx.doi.org/10.1039/c5cp05973a.
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We study mechanisms of solvent-mediated ion interactions with charged surfaces in ionic liquids by molecular dynamics simulations, in an attempt to reveal the main trends that determine ion–electrode interactions in ionic liquids.
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Lashkari, Sima, Sima A. Lashkari, and Rajinder Pal. "Ionic Liquid/Non-Ionic Surfactant Mixtures As Versatile, Non-Volatile Electrolytes: Double-Layer Capacitance and Conductivity." ECS Meeting Abstracts MA2022-01, no. 1 (2022): 5. http://dx.doi.org/10.1149/ma2022-0115mtgabs.
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Self-assembly of ionic liquids (ILs) on 2D materials such as graphene oxide and MXenes facilitated by non-ionic surfactants is a promising approach being increasingly used for the fabrication of high surface area electrodes resulting in high performance supercapacitors. However, the impact that non-ionic surfactants have on double-layer formation and ionic conductivity has yet to be explored. These surfactants are not ionically conductive, have low dielectric constants and high viscosity which are expected to impact the final performance of the electrode. In this study we analyze the effect of adding two commonly used non-ionic surfactants, P123 and Triton X-100 (TX-100) to 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) on the double-layer capacitance formed at a glassy carbon electrode by means of electrochemical impedance spectroscopy. The results, surprisingly suggest an improvement of 75% and 116% in the double layer capacitance measured at the open circuit voltage for 40% of P123 and TX-100, respectively. We also interpret the changes in the DC potential dependence of the capacitance via the most up-to-date understanding of double-layer charging mechanisms with ionic liquids. Similar to previous literature on solvent-based diluents such as polycarbonate and acetonitrile, which cause a similar effect, the improved capacitance is attributed to the reduced Debye length resulting from an increased effective ionic charge accrued by the IL when surrounded by the low-dielectric constant surfactant. Both electrolyte series show the same reduction in ionic conductivity (from 8.5 mS/cm to 1 mS/cm) with respect to concentration regardless of the higher viscosity measured for the P123 electrolyte series. Pulsed field gradient nuclear magnetic resonance, is used to determine the diffusion coefficient for the IL as a function of surfactant concentration and allow us to calculate the effective Stokes radius which is found to shrink significantly as a function of surfactant concentration. Similar to the improved capacitance, this is caused by a reduction in ion-ion interactions and an increase in the average effective charge on each ion. These effects make the electrolyte less sensitive than expected to the increased viscosity caused by addition of the more viscous surfactant phase. The ability to improve the capacitance with non-volatile, low dielectric constant additives, without significantly sacrificing ionic conductivity, opens up an improved avenue for completely non-volatile, non-flammable electrolyte design.
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Charoeythornkhajhornchai, Pollawat, and Anongnat Somwangthanaroj. "Synthesis of Graphene Oxide Grafted with Epoxidized Natural Rubber via Aminosilane Linkage." Materials Science Forum 940 (December 2018): 28–34. http://dx.doi.org/10.4028/www.scientific.net/msf.940.28.
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Graphene oxide was synthesized from graphite by Hummer method and connected with (3-aminopropyl) triethoxysilane to form graphene oxide-aminosilane (GO-Si) linkage. The solution was centrifuged and washed with acetone to remove unreacted aminosilane before grafting with epoxidized natural rubber (ENR). ENR dissolved in toluene solution was mixed with GO-Si particle and dried at room temperature. Then, it was grafted to form graphene oxide grated with ENR via aminosilane linkage (GO-Si-ENR) by heat treatment. GO-Si-ENR was washed in toluene to remove unconnected ENR molecule. The synthesized GO particle in each step was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The possible reaction mechanism was proposed in this research. The aim of this synthesis is to improve natural rubber - graphene interfacial interaction thus the dispersion of GO and GO-Si-ENR particle in natural rubber matrix by solvent mixing process was observed by transmission electron microscopy (TEM).
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Wang, Sijie, Gang Liu, and Junwen Pu. "Enhancement of the strength of biocomposite films via graphene oxide modification." BioResources 13, no. 3 (2018): 6321–31. http://dx.doi.org/10.15376/biores.13.3.6321-6331.
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Chitosan-cellulose film is found in food processing and biotechnology because of its biocompatibility, biodegradability, and antibacterial property. Despite the excellent properties, the presence of intramolecular and intermolecular hydrogen bonds cause cellulose and chitosan to be insoluble in common solvents, resulting in limited mechanical strength. Graphene oxide has heavy oxygen-containing functional groups with excellent mechanical properties, which makes it an ideal filler for reinforcing polymers. In this work, blends of graphene oxide and chitosan-cellulose were successfully produced using 1-ally-3-methylimidazolium chloride ([Amim]Cl) and dimethyl sulfoxide (DMSO) as solvent media. Films were prepared by phase-transfer method and investigated by Fourier transform infrared analysis, scanning electron microscopy, atomic force microscopy, X-ray diffraction, thermogravimetric analysis, and mechanical tests. The absence of the bands corresponding to C=O stretching in graphene oxide and the -NH bending of amides and amines in chitosan, the absence of the diffraction peak at 2θ =11.3° in graphene oxide (XRD), and the improvement of thermal stability and mechanical property provided evidence for the interaction between graphene oxide and chitosan-cellulose.
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Jin, Yezi, Zhijun Xu, Yanan Guo, and Xiaoning Yang. "Molecular-Level Recognition of Interaction Mechanism between Graphene Oxides in Solvent Media." Journal of Physical Chemistry C 122, no. 7 (2018): 4063–72. http://dx.doi.org/10.1021/acs.jpcc.7b12017.
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Nair, Adwaita SR, Subhash Mandal, Debmalya Roy, and N. EswaraPrasad. "Fabrication of cellular structures in thermoplastic polyurethane matrix using carbonaceous nanofillers." IOP Conference Series: Materials Science and Engineering 1219, no. 1 (2022): 012004. http://dx.doi.org/10.1088/1757-899x/1219/1/012004.
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Abstract In the present study, we have synthesized, graphene oxide (GO) by using modified Hummer’s method and reduced graphene oxide(rGO) by using hydrazine hydrate as reducing agent. Since GO and rGO have high surface area and modification of surface is easier, they produce drastic changes in the matrix properties at a very low loading volume. Oxygen functionalities further allow increased interaction with polar polymer composites. Modified hummers method is the most commonly and widely used method of chemical reduction to synthesis graphene oxide as it is rapid and safe. Unlike other method, it is less hazardous and requires less reaction time. Sulfuric acid was used to disperse graphite and NaNO3 and KMNO4 as oxidizing agent. The use of KMNO4 instead of KClO3 reduced the chances of ClO2 explosion and also accelerated the reaction. Characterization of graphene oxide and reduced graphene oxide was done using XRD, SEM, FTIR, Raman spectroscopy and TGA. The synthesized GO and rGO were used as nanofillers for the synthesis of polyurethane nanocomposite. Thermoplastic polyurethane is biodegradable and thus polyurethane nanocomposites have wide application. PU nanocomposites were prepared using thermo-chemical solvent mixing method and their microstructures were investigated using various characterization techniques.
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Cui, Liting, Haining Wang, Sian Chen, et al. "The Interaction Energy between Solvent Molecules and Graphene as an Effective Descriptor for Graphene Dispersion in Solvents." Journal of Physical Chemistry C 125, no. 9 (2021): 5167–71. http://dx.doi.org/10.1021/acs.jpcc.0c10132.
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Rai, K. B., R. P. Yadav, P. M. Shrestha, S. P. Gupta, R. Neupane, and R. R. Ghimire. "Fabrication of Gas Sensor Based on Graphene for the Adsorption of Gases Produced from Waste Material in Kitchen and its Surrounding." Journal of Nepal Physical Society 8, no. 3 (2022): 26–31. http://dx.doi.org/10.3126/jnphyssoc.v8i3.50719.
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Graphene attracted to the researcher with huge attention due to their unique physicochemical properties including high specific surface area and high-speed electron mobility at room temperature. The graphene with several layers was synthesized through liquid phase exfoliation method using high shear force of the magnetic stirrer. This process was performed about 6 hour on the graphite powder and dimethyl-formamide solvent of 0.25 M, 0.5 M and 1 M concentration solution following the microwave treatment for 30 second and sonication for 2 hour at room temperature. The drop-casted exfoliated graphene into glass substrate had G peak and 2D peak. The graphene from 1M concentration had the better quality as compared to the graphene obtained from 0.25M and 0.5M concentration solution. The fabricated gas sensor device with two contact electrodes using exfoliated graphene as a channel material produced the different current (I)–voltage (V) characteristics. The current vs. voltage of bare graphene film without filling of waste harmful gases had the current shifted from 0 mA to 0.0652 mA when the maximum voltage was applied. The current increased nearly from 0.0652 mA to 0.2391 mA after harmful waste gases adjustment at maximum applied voltage. The current through few layers graphene channel after harmful gases filled was found 3.6 times higher than that of the current through the graphene channel without harmful waste gases. This result was due to the adsorption/absorption and interaction of more quantity of harmful waste gases by the exfoliated graphene. So, the device showing some current variation informed that the graphene gas sensor was sensitive to waste gases produced from home kitchen and its surrounding.
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Shtepliuk, Ivan, Maria Santangelo, Mikhail Vagin, et al. "Understanding Graphene Response to Neutral and Charged Lead Species: Theory and Experiment." Materials 11, no. 10 (2018): 2059. http://dx.doi.org/10.3390/ma11102059.
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Deep understanding of binding of toxic Lead (Pb) species on the surface of two-dimensional materials is a required prerequisite for the development of next-generation sensors that can provide fast and real-time detection of critically low concentrations. Here we report atomistic insights into the Lead behavior on epitaxial graphene (Gr) on silicon carbide substrates by thorough complementary study of voltammetry, electrical characterization, Raman spectroscopy, and Density Functional Theory (DFT). It is verified that the epitaxial graphene exhibits quasi-reversible anode reactions in aqueous solutions, providing a well-defined redox peak for Pb species and good linearity over a concentration range from 1 nM to 1 µM. The conductometric approach offers another way to investigate Lead adsorption, which is based on the formations of stable charge-transfer complexes affecting the p-type conductivity of epitaxial graphene. Our results suggest the adsorption ability of the epitaxial graphene towards divalent Lead ions is concentration-dependent and tends to saturate at higher concentrations. To elucidate the mechanisms responsible for Pb adsorption, we performed DFT calculations and estimated the solvent-mediated interaction between Lead species in different oxidative forms and graphene. Our results provide central information regarding the energetics and structure of Pb-graphene interacting complexes that underlay the adsorption mechanisms of neutral and divalent Lead species. Such a holistic understanding favors design and synthesis of new sensitive materials for water quality monitoring.
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Elazab, Hany A., and Tamer T. El-Idreesy. "Polyvinylpyrrolidone - Reduced Graphene Oxide - Pd Nanoparticles as an Efficient Nanocomposite for Catalysis Applications in Cross-Coupling Reactions." Bulletin of Chemical Reaction Engineering & Catalysis 14, no. 3 (2019): 490. http://dx.doi.org/10.9767/bcrec.14.3.3461.490-501.
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This paper reported a scientific approach adopting microwave-assisted synthesis as a synthetic route for preparing highly active palladium nanoparticles stabilized by polyvinylpyrrolidone (Pd/PVP) and supported on reduced Graphene oxide (rGO) as a highly active catalyst used for Suzuki, Heck, and Sonogashira cross coupling reactions with remarkable turnover number (6500) and turnover frequency of 78000 h-1. Pd/PVP nanoparticles supported on reduced Graphene oxide nanosheets (Pd-PVP/rGO) showed an outstanding performance through high catalytic activity towards cross coupling reactions. A simple, reproducible, and reliable method was used to prepare this efficient catalyst using microwave irradiation synthetic conditions. The synthesis approach requires simultaneous reduction of palladium and in the presence of Gaphene oxide (GO) nanosheets using ethylene glycol as a solvent and also as a strong reducing agent. The highly active and recyclable catalyst has so many advantages including the use of mild reaction conditions, short reaction times in an environmentally benign solvent system. Moreover, the prepared catalyst could be recycled for up to five times with nearly the same high catalytic activity. Furthermore, the high catalytic activity and recyclability of the prepared catalyst are due to the strong catalyst-support interaction. The defect sites in the reduced Graphene oxide (rGO) act as nucleation centers that enable anchoring of both Pd/PVP nanoparticles and hence, minimize the possibility of agglomeration which leads to a severe decrease in the catalytic activity. Copyright © 2019 BCREC Group. All rights reserved
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Purwandari, Vivi, Saharman Gea, Basuki Wirjosentono, Agus Haryono, I. Putu Mahendra, and Yasir Arafat Hutapea. "Electrical and Thermal Conductivity of Cyclic Natural Rubber/Graphene Nanocomposite Prepared by Solution Mixing Technique." Indonesian Journal of Chemistry 20, no. 4 (2020): 801. http://dx.doi.org/10.22146/ijc.44791.
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Thermal and electrical conductivity studies of Cyclic Natural Rubber nanocomposite with graphene 1 and 2 phr (G1 and G2) and modified 1 and 2 graphenes (mG1 and mG2) have been carried out. Graphene was activated with cetrimonium bromide (CTAB), was isolated from Sawahlunto coal (Bb) by the Hummer modification method. The nanocomposite was fabricated through the mixing solution method using Xylena as a solvent. The characterizations of nanocomposites which were performed by Fourier Transform Infrared (FT-IR) and X-Ray Diffraction (XRD) reveals an interaction between graphene, CTAB and the CNR matrix. Furthermore, Scanning Electron Magnetic (SEM) and Transmission Electron Microscopy (TEM) indicate the particle size to be smaller and particle distribution is more in accordance with CTAB. Thermal analysis of nanocomposites using Differential Scanning Calorimeter (DSC) showed an increase in thermal conductivity from 3.0084 W/mK to 3.5569 W/mK. Analysis of electrical conductivity using the Two-Point Probe shows 2 phr mG (mG2) capable of increasing electrical conductivity from 0.1170 × 10–4 S/cm to 0.2994 × 10-4 S/cm.
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Wang, Jian, Ryuki Suzuki, Kentaro Ogata, Takuto Nakamura, Aixue Dong, and Wei Weng. "Near-Linear Responsive and Wide-Range Pressure and Stretch Sensor Based on Hierarchical Graphene-Based Structures via Solvent-Free Preparation." Polymers 12, no. 8 (2020): 1814. http://dx.doi.org/10.3390/polym12081814.
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Flexible and wearable electronics have huge potential applications in human motion detection, human–computer interaction, and context identification, which have promoted the rapid development of flexible sensors. So far the sensor manufacturing techniques are complex and require a large number of organic solvents, which are harmful not only to human health but also to the environment. Here, we propose a facile solvent-free preparation toward a flexible pressure and stretch sensor based on a hierarchical layer of graphene nanoplates. The resulting sensor exhibits many merits, including near-linear response, low strain detection limits to 0.1%, large strain gauge factor up to 36.2, and excellent cyclic stability withstanding more than 1000 cycles. Besides, the sensor has an extraordinary pressure range as large as 700 kPa. Compared to most of the reported graphene-based sensors, this work uses a completely environmental-friendly method that does not contain any organic solvents. Moreover, the sensor can practically realize the delicate detection of human body activity, speech recognition, and handwriting recognition, demonstrating a huge potential for wearable sensors.