Journal articles: 'Oxygen Evolution Reaction (OER)'

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Elbaz, Lior, and Wenjamin Moschkowitsch. "Electrocatalyzing Oxygen Evolution Reaction with Nifeooh Aerogels." ECS Meeting Abstracts MA2022-02, no. 44 (October 9, 2022): 1680. http://dx.doi.org/10.1149/ma2022-02441680mtgabs.

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Increasing the production capacity of electrical energy to fulfill the continuously rising global demand, while simultaneously trying to avoid greenhouse gas emissions in the process, and being environmentally sound, is one of the largest challenges of this era.One way to achieve it is to rely on hydrogen for energy storage. Nowadays, most of the hydrogen produced is mainly from fossil fuels, and the emission of detrimental gasses is only shifted. To get to a true green hydrogen, it is necessary to produce it in emissions-free processes. One method to achieve this is to use renewable energies in combination with electrochemical water electrolyzers, in which two distinct chemical reactions take place: the cathodic hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER). Both reaction require catalysts to execute at high rates, and while the HER is considered to be relatively facile and takes place at low overpotentials, the OER requires relatively high overpotentials and high loadings of precious metal catalysts. It is considered the bottleneck reaction. The OER is a four electrons oxidation reaction per generated O2 molecule, and proceeds in four distinct reaction steps. This leads to a very sluggish reaction kinetics and high overpotentials to reach viable current densities. In recent years, more and more non-precious metal OER catalyst have been developed. Most notably is the family of mixed nickel-iron oxyhydroxides (NiFeOOH), which are relatively cheap, selective and efficient catalysts in alkaline media, and their performance has been increased by optimizing the Ni:Fe ratio, adding a third metal that either further increase the performance of the catalyst or/and its stability and other methods. One challenge that still remains is to increase the NiFeOOH surface area, and by that the electrochemically active site density (EASD). In this regard, one class of materials that has been attracting the attention of materials’ scientists in recent years are aerogels. Aerogels can be made from many different materials, such as silicates, carbons, metal organic materials, bio-inspired molecules, metals, and metal oxides. They consist of distinct units which form a porous 3D covalent framework (COF). Because of their diversity, aerogels have many different applications, e.g. as insulators, sensors, or catalysts. In this presentation we will report the synthesis of NixFeyOz aerogels, with a modified easy synthetic method via an epoxide route. These aerogels show much higher utilization of the material and overall increase in mass activity when catalyzing the OER when compared to other NiFeOOH derived materials. They were tested for their OER electrocatalytic activity and to the best of our knowledge these are the first aerogel materials that propagate OER themselves, rather than being used merely as support material for OER catalysts. The catalytic activity depends largely on the Ni:Fe ratio and not the surface area, which can lead to mass transport limitations when too high, showing an optimum for the ratio and the surface area.

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Lin, Shiru, Haoxiang Xu, Yekun Wang, Xiao Cheng Zeng, and Zhongfang Chen. "Directly predicting limiting potentials from easily obtainable physical properties of graphene-supported single-atom electrocatalysts by machine learning." Journal of Materials Chemistry A 8, no. 11 (2020): 5663–70. http://dx.doi.org/10.1039/c9ta13404b.

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The oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are three critical reactions for energy-related applications, such as water electrolyzers and metal–air batteries.

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Wu, Hengbo, Jie Wang, Wei Jin, and Zexing Wu. "Recent development of two-dimensional metal–organic framework derived electrocatalysts for hydrogen and oxygen electrocatalysis." Nanoscale 12, no. 36 (2020): 18497–522. http://dx.doi.org/10.1039/d0nr04458j.

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Developing efficient and low-cost electrocatalysts with unique nanostructures is of great significance for improved electrocatalytic reactions, including the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR).

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Wan, Xin, Yingjie Song, Hua Zhou, and Mingfei Shao. "Layered Double Hydroxides for Oxygen Evolution Reaction towards Efficient Hydrogen Generation." Energy Material Advances 2022 (September 7, 2022): 1–17. http://dx.doi.org/10.34133/2022/9842610.

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Electrochemical water splitting is one of the effective ways to obtain highly pure hydrogen. However, as one of the two half reactions, oxygen evolution reaction (OER) has a high overpotential, resulting in the low-energy utilization efficiency. Therefore, numerous electrocatalysts have been developed to reduce the energy barrier of OER. Among them, layered double hydroxides (LDHs) are excellent OER electrocatalysts with flexible composition and structure, which have been widely investigated in the past decade. Recent studies have been focusing on the identification of active sites for LDHs during OER process, trying to reveal clear reaction mechanism for designing more efficient LDHs electrocatalysts. Hence, this review tries to discuss the advances in identifying active site of LDHs based OER electrocatalysts for efficient hydrogen generation. We first introduce the effect of structure, composition, and defects to the OER performance of LDHs. Furthermore, main attention is paid on the active sites and mechanisms during OER, especially the coordination structures and catalytic mechanisms of active sites. At the end of this review, we put forward the existing problems and shortcomings in this fields, and propose the corresponding solutions, aiming to further promote the development of outstanding OER electrocatalysts towards efficient hydrogen production.

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Morales, Dulce M., Mariya A. Kazakova, Maximilian Purcel, Justus Masa, and Wolfgang Schuhmann. "The sum is more than its parts: stability of MnFe oxide nanoparticles supported on oxygen-functionalized multi-walled carbon nanotubes at alternating oxygen reduction reaction and oxygen evolution reaction conditions." Journal of Solid State Electrochemistry 24, no. 11-12 (June 1, 2020): 2901–6. http://dx.doi.org/10.1007/s10008-020-04667-2.

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Abstract Successful design of reversible oxygen electrocatalysts does not only require to consider their activity towards the oxygen reduction (ORR) and the oxygen evolution reactions (OER), but also their electrochemical stability at alternating ORR and OER operating conditions, which is important for potential applications in reversible electrolyzers/fuel cells or metal/air batteries. We show that the combination of catalyst materials containing stable ORR active sites with those containing stable OER active sites may result in a stable ORR/OER catalyst if each of the active components can satisfy the current demand of their respective reaction. We compare the ORR/OER performances of oxides of Mn (stable ORR active sites), Fe (stable OER active sites), and bimetallic Mn0.5Fe0.5 (reversible ORR/OER catalyst) supported on oxidized multi-walled carbon nanotubes. Despite the instability of Mn and Fe oxide for the OER and the ORR, respectively, Mn0.5Fe0.5 exhibits high stability for both reactions.

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Jeon, Jaeeun, Kyoung Ryeol Park, Kang Min Kim, Daehyeon Ko, HyukSu Han, Nuri Oh, Sunghwan Yeo, Chisung Ahn, and Sungwook Mhin. "CoFeS2@CoS2 Nanocubes Entangled with CNT for Efficient Bifunctional Performance for Oxygen Evolution and Oxygen Reduction Reactions." Nanomaterials 12, no. 6 (March 16, 2022): 983. http://dx.doi.org/10.3390/nano12060983.

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Exploring bifunctional electrocatalysts to lower the activation energy barriers for sluggish electrochemical reactions for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are of great importance in achieving lower energy consumption and higher conversion efficiency for future energy conversion and storage system. Despite the excellent performance of precious metal-based electrocatalysts for OER and ORR, their high cost and scarcity hamper their large-scale industrial application. As alternatives to precious metal-based electrocatalysts, the development of earth-abundant and efficient catalysts with excellent electrocatalytic performance in both the OER and the ORR is urgently required. Herein, we report a core–shell CoFeS2@CoS2 heterostructure entangled with carbon nanotubes as an efficient bifunctional electrocatalyst for both the OER and the ORR. The CoFeS2@CoS2 nanocubes entangled with carbon nanotubes show superior electrochemical performance for both the OER and the ORR: a potential of 1.5 V (vs. RHE) at a current density of 10 mA cm−2 for the OER in alkaline medium and an onset potential of 0.976 V for the ORR. This work suggests a processing methodology for the development of the core–shell heterostructures with enhanced bifunctional performance for both the OER and the ORR.

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Öztürk, Secil, Yu-Xuan Xiao, Dennis Dietrich, Beatriz Giesen, Juri Barthel, Jie Ying, Xiao-Yu Yang, and Christoph Janiak. "Nickel nanoparticles supported on a covalent triazine framework as electrocatalyst for oxygen evolution reaction and oxygen reduction reactions." Beilstein Journal of Nanotechnology 11 (May 11, 2020): 770–81. http://dx.doi.org/10.3762/bjnano.11.62.

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Covalent triazine frameworks (CTFs) are little investigated, albeit they are promising candidates for electrocatalysis, especially for the oxygen evolution reaction (OER). In this work, nickel nanoparticles (from Ni(COD)2) were supported on CTF-1 materials, which were synthesized from 1,4-dicyanobenzene at 400 °C and 600 °C by the ionothermal method. CTF-1-600 and Ni/CTF-1-600 show high catalytic activity towards OER and a clear activity for the electrochemical oxygen reduction reaction (ORR). Ni/CTF-1-600 requires 374 mV overpotential in OER to reach 10 mA/cm2, which outperforms the benchmark RuO2 catalyst, which requires 403 mV under the same conditions. Ni/CTF-1-600 displays an OER catalytic activity comparable with many nickel-based electrocatalysts and is a potential candidate for OER. The same Ni/CTF-1-600 material shows a half-wave potential of 0.775 V for ORR, which is slightly lower than that of commercial Pt/C (0.890 V). Additionally, after accelerated durability tests of 2000 cycles, the material showed only a slight decrease in activity towards both OER and ORR, demonstrating its superior stability.

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Yao, Bin, Youzhou He, Song Wang, Hongfei Sun, and Xingyan Liu. "Recent Advances in Porphyrin-Based Systems for Electrochemical Oxygen Evolution Reaction." International Journal of Molecular Sciences 23, no. 11 (May 27, 2022): 6036. http://dx.doi.org/10.3390/ijms23116036.

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Oxygen evolution reaction (OER) plays a pivotal role in the development of renewable energy methods, such as water-splitting devices and the use of Zn–air batteries. First-row transition metal complexes are promising catalyst candidates due to their excellent electrocatalytic performance, rich abundance, and cheap price. Metalloporphyrins are a class of representative high-efficiency complex catalysts owing to their structural and functional characteristics. However, OER based on porphyrin systems previously have been paid little attention in comparison to the well-described oxygen reduction reaction (ORR), hydrogen evolution reaction, and CO2 reduction reaction. Recently, porphyrin-based systems, including both small molecules and porous polymers for electrochemical OER, are emerging. Accordingly, this review summarizes the recent advances of porphyrin-based systems for electrochemical OER. Firstly, the electrochemical OER for water oxidation is discussed, which shows various methodologies to achieve catalysis from homogeneous to heterogeneous processes. Subsequently, the porphyrin-based catalytic systems for bifunctional oxygen electrocatalysis including both OER and ORR are demonstrated. Finally, the future development of porphyrin-based catalytic systems for electrochemical OER is briefly prospected.

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Rahman, Sheikh Tareq, Kyong Yop Rhee, and Soo-Jin Park. "Nanostructured multifunctional electrocatalysts for efficient energy conversion systems: Recent perspectives." Nanotechnology Reviews 10, no. 1 (January 1, 2021): 137–57. http://dx.doi.org/10.1515/ntrev-2021-0008.

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Abstract Electrocatalysts play a significant performance in renewable energy conversion, supporting several sustainable methods for future technologies. Because of the successful fabrication of distinctive oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) electrocatalysts, bifunctional ORR/OER and HER/OER electrocatalysts have become a hot area of contemporary research. ORR, OER, and HER have gained considerable attention because of their strong performance in different energy conversion and storage devices, including water-splitting devices, fuel cells, and metal–air rechargeable batteries. Therefore, the development of effective nanostructured multifunctional electrocatalysts for ORR, OER, and HER is necessary; and there is a demand for their industrialization for sustainable energy technology. In this review, details of current improvements in multifunctional catalysts for ORR/OER as well as HER/OER are presented, focusing on insight into the theoretical considerations of these reactions through investigation and estimation of different multifunctional catalysts. By analyzing the universal principles for various electrochemical reactions, we report a systematic scheme to clarify the recent trends in catalyzing these reactions over various types of nanostructure catalysts. The relevant reaction pathways and the related activity details for these reactions in the current literature are also included. Overall, the current demands and future outlines for improving the prospects of multifunctional electrocatalysts are discussed.

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Sui, Chenxi, Kai Chen, Liming Zhao, Li Zhou, and Qu-Quan Wang. "MoS2-modified porous gas diffusion layer with air–solid–liquid interface for efficient electrocatalytic water splitting." Nanoscale 10, no. 32 (2018): 15324–31. http://dx.doi.org/10.1039/c8nr04082f.

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The formation and adsorption of bubbles on electrodes weaken the efficiency of gas evolution reactions such as the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) by hindering proton transfer and consuming nucleation energy.

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Li, Nancy, Thomas P. Keane, Samuel S. Veroneau, Ryan G. Hadt, Dugan Hayes, Lin X. Chen, and Daniel G. Nocera. "Template-stabilized oxidic nickel oxygen evolution catalysts." Proceedings of the National Academy of Sciences 117, no. 28 (July 7, 2020): 16187–92. http://dx.doi.org/10.1073/pnas.2001529117.

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Earth-abundant oxygen evolution catalysts (OECs) with extended stability in acid can be constructed by embedding active sites within an acid-stable metal-oxide framework. Here, we report stable NiPbOxfilms that are able to perform oxygen evolution reaction (OER) catalysis for extended periods of operation (>20 h) in acidic solutions of pH 2.5; conversely, native NiOxcatalyst films dissolve immediately. In situ X-ray absorption spectroscopy and ex situ X-ray photoelectron spectroscopy reveal that PbO2is unperturbed after addition of Ni and/or Fe into the lattice, which serves as an acid-stable, conductive framework for embedded OER active centers. The ability to perform OER in acid allows the mechanism of Fe doping on Ni catalysts to be further probed. Catalyst activity with Fe doping of oxidic Ni OEC under acid conditions, as compared to neutral or basic conditions, supports the contention that role of Fe3+in enhancing catalytic activity in Ni oxide catalysts arises from its Lewis acid properties.

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Lhermitte, Charles R., J. Garret Verwer, and Bart M. Bartlett. "Improving the stability and selectivity for the oxygen-evolution reaction on semiconducting WO3 photoelectrodes with a solid-state FeOOH catalyst." Journal of Materials Chemistry A 4, no. 8 (2016): 2960–68. http://dx.doi.org/10.1039/c5ta04747a.

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WO₃ electrodes were synthesized via a sol–gel route followed by the photoelectrochemical deposition of a solid state FeOOH oxygen-evolution catalyst (OEC) to observe its effects on electrode stability and selectivity towards the oxygen evolution reaction (OER).

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Zhang, Pengfei, Hongmei Qiu, Huicong Li, Jiangang He, Yingying Xu, and Rongming Wang. "Nonmetallic Active Sites on Nickel Phosphide in Oxygen Evolution Reaction." Nanomaterials 12, no. 7 (March 29, 2022): 1130. http://dx.doi.org/10.3390/nano12071130.

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Efficient and durable catalysts are crucial for the oxygen evolution reaction (OER). The discovery of the high OER catalytic activity in Ni12P5 has attracted a great deal of attention recently. Herein, the microscopic mechanism of OER on the surface of Ni12P5 is studied using density functional theory calculations (DFT) and ab initio molecular dynamics simulation (AIMD). Our results demonstrate that the H2O molecule is preferentially adsorbed on the P atom instead of on the Ni atom, indicating that the nonmetallic P atom is the active site of the OER reaction. AIMD simulations show that the dissociation of H from the H2O molecule takes place in steps; the hydrogen bond changes from Oa-H⋯Ob to Oa⋯H-Ob, then the hydrogen bond breaks and an H+ is dissociated. In the OER reaction on nickel phosphides, the rate-determining step is the formation of the OOH group and the overpotential of Ni12P5 is the lowest, thus showing enhanced catalytic activity over other nickel phosphides. Moreover, we found that the charge of Ni and P sites has a linear relationship with the adsorption energy of OH and O, which can be utilized to optimize the OER catalyst.

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Priamushko, Tatiana, Rémy Guillet-Nicolas, and Freddy Kleitz. "Mesoporous Nanocast Electrocatalysts for Oxygen Reduction and Oxygen Evolution Reactions." Inorganics 7, no. 8 (August 11, 2019): 98. http://dx.doi.org/10.3390/inorganics7080098.

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Catalyzed oxygen evolution and oxygen reduction reactions (OER and ORR, respectively) are of particular significance in many energy conversion and storage processes. During the last decade, they emerged as potential routes to sustain the ever-growing needs of the future clean energy market. Unfortunately, the state-of-the-art OER and ORR electrocatalysts, which are based on noble metals, are noticeably limited by a generally high activity towards one type of reaction only, high costs and relatively low abundance. Therefore, the development of (bi)functional low-cost non-noble metal or metal-free electrocatalysts is expected to increase the practical energy density and drastically reduce the production costs. Owing to their pore properties and high surface areas, mesoporous materials show high activity towards electrochemical reactions. Among all synthesis methods available for the synthesis of non-noble mesoporous metal oxides, the hard-templating (or nanocasting) approach is one of the most attractive in terms of achieving variable morphology and porosity of the materials. In this review, we thus focus on the recent advances in the design, synthesis, characterization and efficiency of non-noble metal OER and ORR electrocatalysts obtained via the nanocasting route. Critical aspects of these materials and perspectives for future developments are also discussed.

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Fontanesi, Claudio, Massimo Innocenti, Walter Giurlani, Mirko Gazzotti, Marco Bonechi, and Andrea Stefani. "Electrodeposited Ni for the Oxygen Evolution Reaction (OER)." ECS Meeting Abstracts MA2020-02, no. 18 (November 23, 2020): 1529. http://dx.doi.org/10.1149/ma2020-02181529mtgabs.

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Kim, Jeheon, Tomohiro Fukushima, Ruifeng Zhou, and Kei Murakoshi. "Revealing High Oxygen Evolution Catalytic Activity of Fluorine-Doped Carbon in Alkaline Media." Materials 12, no. 2 (January 10, 2019): 211. http://dx.doi.org/10.3390/ma12020211.

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Oxygen evolution reactions (OER) are important reactions for energy conversion. Metal-free carbon-based catalysts potentially contribute to the catalytic materials for OER. However, it has been difficult to understand the intrinsic catalytic activity of carbon materials, due to catalyst decomposition over the course of long-term reactions. Here, we report high oxygen evolution reaction catalytic activity of F-doped carbon in alkaline media. Intrinsic OER activity was evaluated from a combination of measurements using a rotating disk electrode and O2 sensor. The F-doped carbon catalyst is a highly active catalyst, comparable to state-of-the-art precious-metal-based catalysts such as RuO2.

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Ghanashyam, Gyawali, and Hae Kyung Jeong. "Size Effects of MoS2 on Hydrogen and Oxygen Evolution Reaction." Journal of Electrochemical Science and Technology 13, no. 1 (February 28, 2022): 120–27. http://dx.doi.org/10.33961/jecst.2021.00710.

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Molybdenum disulfide (MoS2) has been widely used as a catalyst for the bifunctional activities of hydrogen and oxygen evolution reactions (HER and OER). Here, we investigated size dependent HER and OER performance of MoS2. The smallest size (90 nm) of MoS2 exhibits the lowest overpotential of −0.28 V at −10 mAcm−2 and 1.52 V at 300 mAcm−2 with the smallest Tafel slopes of 151 and 176 mVdec−1 for HER and OER, respectively, compared to bigger sizes (2 μm and 6 μm) of MoS2. The better HER and OER performance is attributed to high electrochemical active surface area (6 × 10−4 cm2) with edge sites and low charge transfer resistance (18.1 Ω), confirming that the smaller MoS2 nanosheets have the better catalytic behavior.

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Putra, Ridwan P., Ihsan Budi Rachman, Hideyuki Horino, and Izabela I. Rzeznicka. "Bifunctional Catalytic Activity of γ-NiOOH toward Oxygen Reduction and Oxygen Evolution Reactions in Alkaline Solutions." Oxygen 2, no. 4 (October 13, 2022): 479–92. http://dx.doi.org/10.3390/oxygen2040031.

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Nickel oxyhydroxides (NiOOHs) are well-known for their superior activity toward oxygen evolution reaction (OER) in alkaline solutions. However, their activity toward oxygen reduction reaction (ORR) has been largely unexplored. There exist three NiOOH polymorphs: α-, β-, and γ-NiOOH, characterized by different interlayer spacing. Although still debated, γ-NiOOH with a large layer spacing has been indicated as the active phase for OER. Here, a highly crystalline γ-NiOOH was prepared in a carbon matrix by the in situ electrochemical transformation of nickel dithiooxamide Ni(dto) in 1 M KOH solution. The catalyst prepared in this way showed low overpotential not only for OER, but also for ORR in alkaline solutions. The onset potential for ORR is ~0.81 V vs. RHE, and the reaction proceeds via the 2e− transfer pathway. The high OER catalytic activity and relatively low ORR overpotential make this nanocomposite catalyst a good candidate for bifunctional OER/ORR catalyst, stable in alkaline solutions.

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Bian, Yaru, Hao Wang, Zhi Gao, Jintang Hu, Dong Liu, and Liming Dai. "A facile approach to high-performance trifunctional electrocatalysts by substrate-enhanced electroless deposition of Pt/NiO/Ni on carbon nanotubes." Nanoscale 12, no. 27 (2020): 14615–25. http://dx.doi.org/10.1039/d0nr03378b.

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Singh, Aditya Narayan, Amir Hajibabaei, Muhammad Hanif Diorizky, Qiankai Ba, and Kyung-Wan Nam. "Remarkably Enhanced Lattice Oxygen Participation in Perovskites to Boost Oxygen Evolution Reaction." Nanomaterials 13, no. 5 (February 27, 2023): 905. http://dx.doi.org/10.3390/nano13050905.

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Enhancing the participation of the lattice oxygen mechanism (LOM) in several perovskites to significantly boost the oxygen evolution reaction (OER) is daunting. With the rapid decline in fossil fuels, energy research is turning toward water splitting to produce usable hydrogen by significantly reducing overpotential for other half-cells’ OER. Recent studies have shown that in addition to the conventional adsorbate evolution mechanism (AEM), participation of LOM can overcome their prevalent scaling relationship limitations. Here, we report the acid treatment strategy and bypass the cation/anion doping strategy to significantly enhance LOM participation. Our perovskite demonstrated a current density of 10 mA cm−2 at an overpotential of 380 mV and a low Tafel slope (65 mV dec−1) much lower than IrO2 (73 mV dec−1). We propose that the presence of nitric acid-induced defects regulates the electronic structure and thereby lowers oxygen binding energy, allowing enhanced LOM participation to boost OER significantly.

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Chen, Junxue, Sijia Li, Zizheng Qu, Zhonglin Li, Ding Wang, Jialong Shen, and Yibing Li. "Study on Oxygen Evolution Reaction Performance of Jarosite/C Composites." Materials 15, no. 2 (January 17, 2022): 668. http://dx.doi.org/10.3390/ma15020668.

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In the electrolysis of water process, hydrogen is produced and the anodic oxygen evolution reaction (OER) dominates the reaction rate of the entire process. Currently, OER catalysts mostly consist of noble metal (NM) catalysts, which cannot be applied in industries due to the high price. It is of great importance to developing low-cost catalysts materials as NM materials substitution. In this work, jarosite (AFe3(SO4)2(OH)6, A = K+, Na+, NH4+, H3O+) was synthesized by a one-step method, and its OER catalytic performance was studied using catalytic slurry (the weight ratios of jarosite and conductive carbon black are 2:1, 1:1 and 1:2). Microstructures and functional groups of synthesized material were analyzed using XRD, SEM, FI-IR, etc. The OER catalytic performance of (NH4)Fe3(SO4)2(OH)6/conductive carbon black were examined by LSV, Tafel, EIS, ECSA, etc. The study found that the OER has the best catalytic performance when the weight ratio of (NH4)Fe3(SO4)2(OH)6 to conductive carbon black is 2:1. It requires only 376 mV overpotential to generate current densities of 10 mA cm−2 with a small Tafel slope (82.42 mV dec−1) and large Cdl value (26.17 mF cm−2).

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Cheng, J., P. Ganesan, Z. Wang, M. Zhang, G. Zhang, N. Maeda, J. Matsuda, M. Yamauchi, B. Chi, and N. Nakashima. "Bifunctional electrochemical properties of La_0.8Sr_0.2Co_0.8M_0.2O_3−δ (M = Ni, Fe, Mn, and Cu): efficient elemental doping based on a structural and pH-dependent study." Materials Advances 3, no. 1 (2022): 272–81. http://dx.doi.org/10.1039/d1ma00632k.

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Perovskite oxides with a low cost and high catalytic activity are considered as suitable candidates for the oxygen evolution reaction (OER)/oxygen reduction reaction (ORR), but most of them favour only either the ORR or the OER.

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Badreldin, Ahmed, Aya E. Abusrafa, and Ahmed Abdel-Wahab. "Oxygen-deficient perovskites for oxygen evolution reaction in alkaline media: a review." Emergent Materials 3, no. 5 (September 21, 2020): 567–90. http://dx.doi.org/10.1007/s42247-020-00123-z.

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AbstractOxygen vacancies in complex metal oxides and specifically in perovskites are demonstrated to significantly enhance their electrocatalytic activities due to facilitating a degree of control in the material’s intrinsic properties. The reported enhancement in intrinsic OER activity of oxygen-deficient perovskites surfaces has inspired their fabrication via a myriad of schemes. Oxygen vacancies in perovskites are amongst the most favorable anionic or Schottky defects to be induced due to their low formation energies. This review discusses recent efforts for inducing oxygen vacancies in a multitude of perovskites, including facile and environmentally benign synthesis strategies, characterization techniques, and detailed insight into the intrinsic mechanistic modulation of perovskite electrocatalysts. Experimental, analytical, and computational techniques dedicated to the understanding of the improvement of OER activities upon oxygen vacancy induction are summarized in this work. The identification and utilization of intrinsic activity descriptors for the modulation of configurational structure, improvement in bulk charge transport, and favorable inflection of the electronic structure are also discussed. It is our foresight that the approaches, challenges, and prospects discussed herein will aid researchers in rationally designing highly active and stable perovskites that can outperform noble metal-based OER electrocatalysts.

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Ham, Kahyun, Sukhwa Hong, Sinwoo Kang, Kangwoo Cho, and Jaeyoung Lee. "Active Site Formation in Oxygen Deficient Cobalt Antimonate for Oxygen Evolution Reaction in Alkaline Media." ECS Meeting Abstracts MA2022-01, no. 34 (July 7, 2022): 1389. http://dx.doi.org/10.1149/ma2022-01341389mtgabs.

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Electrochemical water splitting is the one of the promising ways to obtain hydrogen from aqueous media. Oxygen evolution reaction (OER) at the anode is the rate-determining step due to the sluggish kinetics, which leads to reducing energy efficiency. Recently, anion exchange membrane water splitting has been considered as an alternative way because of its capability of producing hydrogen of high purity and the availability of iron-triad element-based catalysts because of their thermodynamically stability in alkaline media. Besides, cobalt oxides such as spinel, layered double hydroxide are being investigated as active OER electrocatalyst. Among them, the spinel-type Co3O4, which contains one Co2+ in the tetrahedral site and two Co3+ ions in the octahedral site, exhibits outstanding OER performance in alkaline media and has been actively investigated. In this study, we investigated oxygen-deficient cobalt antimonate oxide (CoSb2O6) as OER catalyst in alkaline media, which has unique crystal structure and contains abundant octahedral Co2+ compared to spinel-type cobalt oxide. Through in situ X-ray absorption near-edge structure analysis, we observed most of octahedral Co2+ ions were oxidized to Co4+ at OER potential, which leaded to increase the OER activity by extending the active site. We also carried out anion exchange membrane water splitting to confirm the availability as the anode catalyst to produce H2 gas.

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Tang, Huang, Deshuai Yang, Mengfei Lu, Shaoxi Kong, Yanghui Hou, Duanduan Liu, Depei Liu, et al. "Spin unlocking oxygen evolution reaction on antiperovskite nitrides." Journal of Materials Chemistry A 9, no. 45 (2021): 25435–44. http://dx.doi.org/10.1039/d1ta07561f.

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The spin state change of Fe3+ ions induced the paramagnetic Fe0.5Ni0.5OOH shell on the ferromagnetic Cu0.5NFe3Ni0.5 core via superexchange interaction, facilitating charge transfer and oxygen species ad(de)sorption for boosted OER performance.

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Hong, Yu-Rim, Sungwook Mhin, Jiseok Kwon, Won-Sik Han, Taeseup Song, and HyukSu Han. "Synthesis of transition metal sulfide and reduced graphene oxide hybrids as efficient electrocatalysts for oxygen evolution reactions." Royal Society Open Science 5, no. 9 (September 2018): 180927. http://dx.doi.org/10.1098/rsos.180927.

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The development of electrochemical devices for renewable energy depends to a large extent on fundamental improvements in catalysts for oxygen evolution reactions (OERs). OER activity of transition metal sulfides (TMSs) can be improved by compositing with highly conductive supports possessing a high surface-to-volume ratio, such as reduced graphene oxide (rGO). Herein we report on the relationship between synthetic conditions and the OER catalytic properties of TMSs and rGO (TMS–rGO) hybrids. Starting materials, reaction temperature and reaction time were controlled to synergistically boost the OER catalytic activity of TMS–rGO hybrids. Our results showed that (i) compared with sulfides, hydroxides are favourable as starting materials to produce the desired TMS–rGO hybrid nanostructure and (ii) high reaction temperatures and longer reaction times can increase physico-chemical interaction between TMSs and rGO supports, resulting in highly efficient OER catalytic activity.

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Wang, Hongxia, Kelvin H. L. Zhang, Jan P. Hofmann, Victor A. de la Peña O'Shea, and Freddy E. Oropeza. "The electronic structure of transition metal oxides for oxygen evolution reaction." Journal of Materials Chemistry A 9, no. 35 (2021): 19465–88. http://dx.doi.org/10.1039/d1ta03732c.

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In this review article, we summarise the key electronic features of transition metal oxides that govern their OER catalytic properties, and how such electronic descriptors are applied for OER electrocatalysts design.

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Zheng, Xingqun, Ling Zhang, Wei He, Li Li, and Shun Lu. "Heteroatom-Doped Nickel Sulfide for Efficient Electrochemical Oxygen Evolution Reaction." Energies 16, no. 2 (January 12, 2023): 881. http://dx.doi.org/10.3390/en16020881.

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Heteroatom doping is an effective strategy to regulate electrocatalysts for the oxygen evolution reaction (OER). Nonmetal heteroatoms can effectively engineer geometric and electronic structures and activating surface sites of catalysts due to their unique radius and the electronegativity of nonmetal atoms. Hence, the surface geometric and electronic structure and activity of nonmetal atoms (X, X = B, C, N, O, P)-doped Ni3S2 (X-Ni3S2) were studied to screen high-performance Ni3S2-based OER electrocatalysts through density functional theory calculation. Theoretical results demonstrated that dopants in X-Ni3S2 can alter bond length and charge of surface, modify active sites for intermediates adsorption, and adjust the theoretical overpotential. Among all dopants, C can effectively modulate surface structure, activate surface sites, weaken the adsorption of key intermediates, decrease theoretical overpotential, and enable C-Ni3S2 with the best theoretical OER activity among all X-Ni3S2 with the lowest theoretical overpotential (0.46 eV). Further experimental results verified that the synthesized C-Ni3S2 performed an improved OER activity in the alkaline condition with a considerably enhanced overpotential of 261 mV at 10 mA cm−2 as well as a Tafel slope of 95 mV dec−1 compared to pristine Ni3S2.

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Altaf, Amna, Manzar Sohail, Ayman Nafady, Rashid G. Siddique, Syed Shoaib Ahmad Shah, and Tayyaba Najam. "Facile Synthesis of PdO.TiO2 Nanocomposite for Photoelectrochemical Oxygen Evolution Reaction." Molecules 28, no. 2 (January 6, 2023): 572. http://dx.doi.org/10.3390/molecules28020572.

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The rapid depletion of fossil fuels and environmental pollution has motivated scientists to cultivate renewable and green energy sources. The hydrogen economy is an emerging replacement for fossil fuels, and photocatalytic water splitting is a suitable strategy to produce clean hydrogen fuel. Herein, the photocatalyst (PdO.TiO2) is introduced as an accelerated photoelectrochemical oxygen evolution reaction (OER). The catalyst showed significant improvement in the current density magnitude from 0.89 (dark) to 4.27 mA/cm2 (light) during OER at 0.5 V applied potential. The as-synthesized material exhibits a Tafel slope of 170 mVdec−1 and efficiency of 0.25% at 0.93 V. The overall outcomes associated with the photocatalytic activity of PdO.TiO2 demonstrated that the catalyst is highly efficient, thereby encouraging researchers to explore more related catalysts for promoting facile OER.

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Qu, Huiying, Xiwen He, Yibo Wang, and Shuai Hou. "Electrocatalysis for the Oxygen Evolution Reaction in Acidic Media: Progress and Challenges." Applied Sciences 11, no. 10 (May 11, 2021): 4320. http://dx.doi.org/10.3390/app11104320.

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The oxygen evolution reaction (OER) is the efficiency-determining half-reaction process of high-demand, electricity-driven water splitting due to its sluggish four-electron transfer reaction. Tremendous effects on developing OER catalysts with high activity and strong acid-tolerance at high oxidation potentials have been made for proton-conducting polymer electrolyte membrane water electrolysis (PEMWE), which is one of the most promising future hydrogen-fuel-generating technologies. This review presents recent progress in understanding OER mechanisms in PEMWE, including the adsorbate evolution mechanism (AEM) and the lattice-oxygen-mediated mechanism (LOM). We further summarize the latest strategies to improve catalytic performance, such as surface/interface modification, catalytic site coordination construction, and electronic structure regulation of catalytic centers. Finally, challenges and prospective solutions for improving OER performance are proposed.

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Choi, Yusong, Tae-Young Ahn, Ji-Youn Kim, Eun Hye Lee, and Hye-Ryeon Yu. "Massively synthesizable nickel-doped 1T-MoS₂ nanosheet catalyst as an efficient tri-functional catalyst." RSC Advances 13, no. 26 (2023): 18122–27. http://dx.doi.org/10.1039/d3ra03016d.

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A nickel (Ni)-doped 1T-MoS2 catalyst, an efficient tri-functional hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) catalyst, was massively synthesized at high pressure (over 15 bar).

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Tang, Yongfu, Hongbin Yang, Jiaojiao Sun, Meirong Xia, Wenfeng Guo, Like Yu, Jitong Yan, Jia Zheng, Limin Chang, and Faming Gao. "Phase-pure pentlandite Ni4.3Co4.7S8 binary sulfide as an efficient bifunctional electrocatalyst for oxygen evolution and hydrogen evolution." Nanoscale 10, no. 22 (2018): 10459–66. http://dx.doi.org/10.1039/c8nr02402b.

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Dogutan, Dilek K., D. Kwabena Bediako, Daniel J. Graham, Christopher M. Lemon, and Daniel G. Nocera. "Proton-coupled electron transfer chemistry of hangman macrocycles: Hydrogen and oxygen evolution reactions." Journal of Porphyrins and Phthalocyanines 19, no. 01-03 (January 2015): 1–8. http://dx.doi.org/10.1142/s1088424614501016.

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The splitting of water into its constituent elements is an important solar fuels conversion reaction for the storage of renewable energy. For each of the half reactions of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), multiple protons and electrons must be coupled to avoid high-energy intermediates. To understand the mechanistic details of the PCET chemistry that underpins HER and OER, we have designed hangman porphyrin and corrole catalysts. In these hangman constructs, a pendant acid/base functionality within the secondary coordination sphere is "hung" above the macrocyclic redox platform on which substrate binds. The two critical thermodynamic properties of a PCET event, the redox potential and pKa may be tuned with the macrocycle and hanging group, respectively. This review outlines the synthesis of these catalysts, as well as the examination of the PCET kinetics of hydrogen and oxygen evolution by the hangman catalysts. The insights provided by these systems provide a guide for the design of future HER and OER catalysts that use a secondary coordination sphere to manage PCET.

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He, Junying, Yuqin Zou, and Shuangyin Wang. "Defective glycerolatocobalt(ii) for enhancing the oxygen evolution reaction." Chemical Communications 55, no. 85 (2019): 12861–64. http://dx.doi.org/10.1039/c9cc06607a.

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Ikezawa, Atsunori, Kotaro Seki, and Hajime Arai. "Rational Placement of Catalysts for Oxygen Reduction and Evolution Reactions Based on the Reaction Sites in Porous Gas Diffusion Electrodes." ECS Meeting Abstracts MA2022-02, no. 4 (October 9, 2022): 522. http://dx.doi.org/10.1149/ma2022-024522mtgabs.

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Metal-air secondary batteries using alkaline electrolyte solutions are promising candidates for next-generation large-scale energy storage systems because of their potential high capacity, low cost, and high safety standard. However, large overpotential of bifunctional air electrodes hindered their wide applications. Recently, increasing research on electrocatalysts for oxygen reduction reaction (ORR) and oxygen reduction reaction (OER) has been conducted to reduce the overpotential, and many active catalysts have been developed. On the other hand, formation of reaction sites is also important since the reaction sites for ORR and OER are basically different1. In this work, we investigated the reaction sites in porous gas diffusion electrodes (GDE) and constructed a GDE with a double-layered catalyst layer based on the difference in the reaction sites for ORR and OER2. La0.6Ca0.4CoO3 (LCCO, bifunctional catalyst), La0.4Sr0.6MnO3 (LSMO, ORR catalyst) and Ca2FeCoO5 (CFCO, OER catalyst) were synthesized by the polymerized complex method. Porous gas diffusion electrodes are constructed by the hot-press method. Catalyst layers were composed of the prepared catalyst (50 wt%), graphitized carbon black (35 wt%), and poly(tetrafluoroethylene) (15 wt%). Gas diffusion layers (GDL) were commercial carbon papers (TGP-H-030H, Chemix). IR-corrected polarization curves were measured by the constant current and AC impedance measurements. Oxygen diffusion resistances for ORR and OER were estimated from the difference in the steady-state potential between pure oxygen and air atmosphere (⊿E = |E O2 – Eair|). Larger increase in ⊿E indicates larger oxygen diffusion resistances in the oxygen reaction processes3. Figure 1 (a, b) shows ⊿E-I curves of LCCO-GDE for ORR and OER in 4.0 and 8.0 dm–3 KOHaq. The oxygen permeability(D O2×C O2) in 4.0 dm–3 KOHaq is 16 times as large as that in 8.0 dm–3 KOHaq while the ion conductivities of these electrolyte solutions are at the same extent. The increase in ⊿E for ORR was larger in 8.0 dm–3 KOHaq, indicating dissolved oxygen involved in the ORR process. In contrast, the ⊿E for OER was nearly negligible in these electrolyte solutions, suggesting that oxygen was mainly transported as bubbles. We also measured ⊿E-I curves of the LCCO-GDE in 8.0 dm–3 KOHaq having different catalyst layer thicknesses. The increases in ⊿E were almost independent of the catalyst layer thicknesses for ORR and OER, suggesting that the reaction sites were concentrated in the catalyst layer. Finally, we compared polarization curves of the GDEs with single-layered catalyst layer (LSMO+CFCO|DGL-GDE) and double-layered catalyst layers (LSMO|CFCO|GDL-GDE and CFCO|LSMO|GDL-GDE) to identify the reaction sites for ORR and OER (Fig. 1 (c, d)). The smallest overpotential of CFCO|LSMO|GDL-GDE for both ORR and OER showed that the reaction sites for ORR and OER were concentrated at the electrolyte-side and gas-side, respectively. In addition, CFCO|LSMO|GDL-GDE showed higher durability than LSMO+CFCO|DGL-GDE. From these results, it can be concluded that the placement of the ORR and OER catalysts on the electrolyte-side and gas-side of the CL can improve both activity and durability of the bifunctional air electrode. References [1] A. Ikezawa, K. Miyazaki, T. Fukutsuka, T. Abe, Electrochem. Commun., 84, 53-56 (2017). [2] A. Ikezawa, K. Seki and H. Arai, Electrochim. Acta, 394, 139128 (2021). [3] A. Kaisheva, I. Iliev, S. Gamburzev, J. Power Sources, 13, 181-195 (1984). Figure 1

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Li, Xiang, Hao Wang, Zhiming Cui, Yutao Li, Sen Xin, Jianshi Zhou, Youwen Long, Changqing Jin, and John B. Goodenough. "Exceptional oxygen evolution reactivities on CaCoO3 and SrCoO3." Science Advances 5, no. 8 (August 2019): eaav6262. http://dx.doi.org/10.1126/sciadv.aav6262.

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We investigated the roles of covalent bonding, separation of surface oxygen, and electrolyte pH on the oxygen evolution reaction (OER) on transition metal oxides by comparing catalytic onset potentials and activities of CaCoO3 and SrCoO3. Both cubic, metallic perovskites have similar CoIV intermediate spin states and onset potentials, but a substantially smaller lattice parameter and shorter surface oxygen separation make CaCoO3 a more stable catalyst with increased OER activity. The onset potentials are similar, occurring where H+ is removed from surface -OH−, but two competing surface reactions determine the catalytic activity. In one, the surface -O− is attacked by electrolyte OH− to form the surface -OOH−; in the other, two -O− form a surface peroxide ion and an oxygen vacancy with electrolyte OH− attacking the oxygen vacancy. The second pathway can be faster if the surface oxygen separation is smaller.

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Kim, Yohan, Seongmin Kim, Minyoung Shim, Yusik Oh, Kug-Seung Lee, Yousung Jung, and Hye Ryung Byon. "Alteration of Oxygen Evolution Mechanisms in Layered LiCoO₂ Structures By Intercalation of Alkali Metal Ions." ECS Meeting Abstracts MA2022-01, no. 34 (July 7, 2022): 1356. http://dx.doi.org/10.1149/ma2022-01341356mtgabs.

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The word ‘Sustainability’, including carbon neutrality, has dominated the direction of social development over the past decade. In particular, energy conversion reactions through electrochemical methods are one of the efficient methods of obtaining small carbon footprint fuels. The oxygen evolution reaction (OER) is a key step in determining the overall reaction efficiency of fuel-related electrochemical reactions such as CO2 reduction reaction and H2 evolution reaction. However, electron transfer is sluggish for OER due to 4 electrons per one O2 molecule. This promotes multiple studies on the metal oxide electrocatalyst structure. The Alkali-transition metal oxides with the layered structure are one of the attractive OER electrocatalyst series. For example, lithium cobalt oxide (LiCoO2, LCO) presented OER activity through Li+ extraction (delithiation) from the lattice structure. In this work, we investigated the insertion effect of large alkaline cations (A+: Na+, K+, and Cs+) at the delithiated LCO for OER activity and stability. The intercalations of hydrated Na+ and K+ induced significant phase transformation of the delithiated LCO structure. In addition, the relative ratio between Co and alkali metal species determined the average Co oxidation state of LCO. We found that OER activity was improved in the order of Li+ < Na+ < K+, which was associated with the increased Co valence state and the Co-O bond covalency. Consistently, density functional theory (DFT) simulation also predicted the formation of efficient OER active sites by the K+ insertion. In comparison, Cs+ insertion exhibited the highest OER activity and demonstrated different OER processes. Due to the larger Cs+ size, the cation insertion was predominantly achieved at the delithiated LCO surface, resulting in imposing tensile strain to the surface edge. This catalyst showed the significant pH dependency on the OER property, suggesting the lattice-oxygen-based pathway for LCO. However, the bulk structure was preserved with little phase transformation, demonstrating better OER stability than others. In the presentation, I will discuss the catalytic activity responsible for the cation sizes and two different mechanisms in detail. Figure 1

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Singh, Harish, Manashi Nath, and Wipula Priya Rasika Liyanage. "Metal Selenide Anchored Carbon Nanotube for Boosted Oxygen Evolution Reaction." ECS Meeting Abstracts MA2022-01, no. 7 (July 7, 2022): 631. http://dx.doi.org/10.1149/ma2022-017631mtgabs.

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The oxygen evolution represents an important reaction in electrochemical water splitting and metal-air batteries. To deal with the increasing energy crisis and demand for sustainable clean energy, production of low-cost, high-efficiency, and robust oxygen evolution reaction (OER) electrocatalysts is urgently needed. Recently, transition metal chalcogenides (TMCs) have been used as active electrocatalysts for OER because of their high electrical conductivity and enhanced electrochemical activity. These chalcogenides based electrocatalysts show unprecedented high efficiency for OER exhibiting very low overpotentials, thereby surpassing state-of-the-art precious metal oxides or hydroxide-based catalysts. Carbon nanostructures have been shown to significantly improve their electrocatalytic performance even further. In the present work, nickel selenide nanorods (NRs) were grown inside carbon nanotubes (NiSe@CNT) through chemical vapor deposition (CVD) wherein, the carbon nanotube formed in-situ wrapping around the growing nickel selenide nanorods. Such intimate intermixing is expected to aid in rapid electron transfer from the catalyst composite and yield significantly higher current density. The encapsulation with a CNT shell can also expectedly increase stability of the selenide phase with respect to corrosion and anion leaching. Electrocatalytic behavior was explored by various electrochemical studies, including linear sweep voltammetry (LSV), chronoamperometric experiments, electrochemical surface area determination, and Tafel slope determination, under highly alkaline condition. It was observed that this NiSe@CNT composites showed enhanced electrocatalytic activity for OER. Our results indicate that the self-grown CNT around nickel selenide increases catalytic activity of this hybrid nanostructure due to an increased number of catalytic sites and electronic conductivity of the nanocomposite. The overpotential at 10 mA cm-2 for the as-synthesized NiSe@CNT catalyst is 270 mV which is much better than precious metal based electrocatalysts for OER, such as RuO2 and IrO2. In addition, the current-voltage plots were superimposable before and after 40 h of chronoamperometry test, confirming that the as-synthesized catalyst gives stable electrocatalytic OER activity in 1 M KOH medium for an extended time period. The as-synthesized catalyst was characterized by XRD, Raman spectroscopy, XPS and TEM for morphology, elemental and chemical compositions. Keywords: oxygen evolution reaction, carbon nanotubes, In-situ wrapping Figure 1

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Jiang, Bo, Jeonghun Kim, Yanna Guo, Kevin C. W. Wu, Saad M. Alshehri, Tansir Ahamad, Norah Alhokbany, Joel Henzie, and Yusuke Yamachi. "Efficient oxygen evolution on mesoporous IrOx nanosheets." Catalysis Science & Technology 9, no. 14 (2019): 3697–702. http://dx.doi.org/10.1039/c9cy00302a.

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Yang, Xiaohang, Zhen Feng, and Zhanyong Guo. "Theoretical Investigation on the Hydrogen Evolution, Oxygen Evolution, and Oxygen Reduction Reactions Performances of Two-Dimensional Metal-Organic Frameworks Fe3(C2X)12 (X = NH, O, S)." Molecules 27, no. 5 (February 24, 2022): 1528. http://dx.doi.org/10.3390/molecules27051528.

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Two-dimensional metal-organic frameworks (2D MOFs) inherently consisting of metal entities and ligands are promising single-atom catalysts (SACs) for electrocatalytic chemical reactions. Three 2D Fe-MOFs with NH, O, and S ligands were designed using density functional theory calculations, and their feasibility as SACs for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) was investigated. The NH, O, and S ligands can be used to control electronic structures and catalysis performance in 2D Fe-MOF monolayers by tuning charge redistribution. The results confirm the Sabatier principle, which states that an ideal catalyst should provide reasonable adsorption energies for all reaction species. The 2D Fe-MOF nanomaterials may render highly-efficient HER, OER, and ORR by tuning the ligands. Therefore, we believe that this study will serve as a guide for developing of 2D MOF-based SACs for water splitting, fuel cells, and metal-air batteries.

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Gond, Ritambhara, Sai Pranav Vanam, and Prabeer Barpanda. "Na2MnP2O7 polymorphs as efficient bifunctional catalysts for oxygen reduction and oxygen evolution reactions." Chemical Communications 55, no. 77 (2019): 11595–98. http://dx.doi.org/10.1039/c9cc04680a.

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Two polymorphs of pyrophosphate Na₂MnP₂O₇ (P1̄ NMPy and P1 NMPy) were prepared by solid-state synthesis. Both polymorphs exhibited promising oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalytic activities.

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Shi, Qiurong, Chengzhou Zhu, Dan Du, and Yuehe Lin. "Robust noble metal-based electrocatalysts for oxygen evolution reaction." Chemical Society Reviews 48, no. 12 (2019): 3181–92. http://dx.doi.org/10.1039/c8cs00671g.

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The oxygen evolution reaction (OER) is a kinetically sluggish anodic reaction that requires rationalized compositions and structures for achieving highly efficient and reliable noble metal-based electrocatalysts in acidic electrolyte.

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Kim, Myeong-Geun, and Sung Jong Yoo. "Surface Reconstruction of Iridium Nanoparticles for Enhanced Oxygen Evolution Reaction in Alkaline Medium." ECS Meeting Abstracts MA2022-01, no. 34 (July 7, 2022): 1400. http://dx.doi.org/10.1149/ma2022-01341400mtgabs.

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An electrochemical water splitting is a promising technology that can generate green hydrogen using renewable energy sources. However, the sluggish oxygen evolution reaction (OER) in an anodic side hinders their large scale applications. Many efforts have been focused on developing efficient electrocatalysts; iridium-based catalysts have gained much attentions due to remarkable intrinsic activities and high stability. Technically, however, the properties are derived from amorphous iridium oxide (IrOx) rather than metallic Ir. During an electrochemical activation process, the Ir metal is easily converted into oxidized species with multiple oxidation states of iridium, which are highly active toward OER. Similarly, many catalysts undergo changes during OER process (e.g., oxidation of precatalysts), resulting in enhancement of activities for OER beyond corresponding original catalysts. Accordingly, the reconstruction process involving surface oxidation and leaching of metal cations should be investigated to develop efficient OER electrocatalysts. Herein, we prepared chalcogen atom modified Ir/IrOx core/shell nanoparticles for enhanced alkaline OER performances (electrolyte: 1M KOH). The S-modified Ir/IrOx exhibited remarkable OER performances with current density of 10 mA cm−2 at overpotentials as low as 180 mV. Incorporation of chalcogen atoms induce surface reconstruction of the Ir/IrOx nanoparticles during OER measurements. It was observed that electrocatalytic activities of Ir/IrOx were varied depending on the type and concentration of chalcogen atoms. There were no observable morphological and structural changes in Ir/IrOx electrocatalyst, whereas the atomic ratio of chalcogen atoms noticeably decreased after OER tests. The result suggests that incorporated chalcogen atoms play a role in modifying the surface of Ir nanoparticles, rather than participating OER as active sites. In addition, XPS measurements were conducted in order to detect changes in chemical states of the catalysts during electrochemical process. We thus believe that the chalcogen atom induced surface reconstruction can be the strategy to efficiently improve the various electrochemical reactions.

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Bathula, Chinna, Abhishek Meena, Sankar Sekar, Aditya Narayan Singh, Ritesh Soni, Adel El-Marghany, Ramasubba Reddy Palem, and Hyun-Seok Kim. "Self-Assembly of Copper Oxide Interfaced MnO2 for Oxygen Evolution Reaction." Nanomaterials 13, no. 16 (August 13, 2023): 2329. http://dx.doi.org/10.3390/nano13162329.

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Designing efficient electrocatalytic systems through facile synthesis remains a formidable task. To address this issue, this paper presents the design of a combination material comprising two transition metal oxides (copper oxide and manganese oxide (CuO/MnO2)), synthesized using a conventional microwave technique to efficiently engage as an active oxygen evolution reaction (OER) catalyst. The structural and morphological properties of the composite were confirmed by the aid of X-ray diffraction (XRD) studies, field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive spectrometry (EDS). FESEM clearly indicated well-aligned interlacing of CuO with MnO2. The OER performance was carried out in 1 M KOH. The assembled CuO/MnO2 delivered a benchmark current density (j = 10 mA cm−2) at a minimal overpotential (η = 294 mV), while pristine CuO required a high η (316 mV). Additionally, the CuO/MnO2 electrocatalyst exhibited stability for more than 15 h. These enhanced electrochemical performances were attributed to the large volume and expanded diameter of the pores, which offer ample surface area for catalytic reactions to boost OER. Furthermore, the rate kinetics of the OER are favored in composite due to low Tafel slope (77 mV/dec) compared to CuO (80 mV/dec).

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Miao, Bo-Qiang, Yi-Ming Liu, Tian-Jiao Wang, Yu Ding, and Yu Chen. "One-dimensional cobalt oxide nanotubes with rich defect for oxygen evolution reaction." Nanotechnology 33, no. 7 (November 25, 2021): 075401. http://dx.doi.org/10.1088/1361-6528/ac3702.

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Abstract For the electrochemcial hydrogen production, the oxygen evolution reaction (OER) is a pivotal half-reaction in water splitting. However, OER suffers sluggish kinetics and high overpotential, leading to the increase of overall energy consumption and decrease of the energy efficiency. In this work, high-quality cobalt oxide porous nanotubes (Co3O4-PNTs) are easily obtained by simple self-template approach. One-dimensional (1D) porous structure provides the large specific surface area, enough abundant active atoms and effective mass transfer. In addition, Co3O4-PNTs also own self-stability of 1D architecture, benefitting the their durability for electrocatalytic reaction. Thus, Co3O4-PNTs with optimal annealing temperature and time reveal the attractive alkaline OER performance (Tafel slope of 56 mV dec−1 and 323 mV overpotential at 10 mA cm−2), which outperform the Co3O4 nanoparticles and benchmark commercial RuO2 nanoparticles. Furthermore, Co3O4-PNTs also exhibit excellent OER durability for least 10 h at the 10 mA cm−2. Overall, Co3O4-PNTs with low cost can be serve as a highly reactive and economical catalyst for OER.

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Salvatore, D. A., B. Peña, K. E. Dettelbach, and C. P. Berlinguette. "Photodeposited ruthenium dioxide films for oxygen evolution reaction electrocatalysis." Journal of Materials Chemistry A 5, no. 4 (2017): 1575–80. http://dx.doi.org/10.1039/c6ta09094j.

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Zhang, Xiaoyun, Yuxin Liu, Xiaoshuang Ma, Xiaojin Liu, Renyun Zhang, and Yuqiao Wang. "Metal–Support Interaction of Carbon–Based Electrocatalysts for Oxygen Evolution Reaction." Nanoenergy Advances 3, no. 1 (March 2, 2023): 48–72. http://dx.doi.org/10.3390/nanoenergyadv3010004.

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Metal–support interaction (MSI) is considered a key effect of electronic and geometric structures of catalysts on tuning catalytic performance. The oxygen evolution reaction (OER) is a crucial process during energy conversion and storage. However, the OER process requires the help of noble metal catalysts to reduce the reaction overpotential, enhance reactivity with intermediates, and maintain good operating stability. Carbon–supported metal catalysts have been considered candidates for noble metal catalysts for OER. MSI occurs at the interface of carbon supports and metals, affecting the catalytic performance through electronic and geometric modulation. MSI can influence the catalytic performance and change reaction pathways from charge redistribution, electron transfer, chemical coordination and bonding, and steric effect. Connecting MSI effects with the OER mechanism can provide theoretical guidance and a practical approach to the design of efficient catalysts, including the modulation of particle size, morphology, heteroatom doping, defect engineering, and coordination atom and number. Advantage can be taken of MSI modulation between metal compounds and carbon supports to provide guidance for catalyst design.

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Choi, Yun-Hyuk. "VO2 as a Highly Efficient Electrocatalyst for the Oxygen Evolution Reaction." Nanomaterials 12, no. 6 (March 12, 2022): 939. http://dx.doi.org/10.3390/nano12060939.

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Herein, we report high electrocatalytic activity of monoclinic VO2 (M1 phase) for the oxygen evolution reaction (OER) for the first time. The single-phase VO2 (M1) nanoparticles are prepared in the form of uniformly covering the surface of individual carbon fibers constituting a carbon fiber paper (CFP). The VO2 nanoparticles reveal the metal-insulator phase transition at ca. 65 °C (heating) and 62 °C (cooling) with low thermal hysteresis, indicating a high concentration of structural defect which is considered a grain boundary among VO2 nanoparticles with some particle coalescence. Consequently, the VO2/CFP shows a high electrocatalytic OER activity with the lowest η10 (350 mV) and Tafel slope (46 mV/dec) values in a 1 M aqueous solution of KOH as compared to those of the vacuum annealed V2O5 and the hydrothermally grown VO2 (M1), α-V2O5, and γ′-V2O5. The catalytically active site is considered V4+ components and V4+/5+ redox couples in VO2. The oxidation state of V4+ is revealed to be more favorable to the OER catalysis compared to that of V5+ in vanadium oxide through comparative studies. Furthermore, the amount of V5+ component is found to be increased on the surface of VO2 catalyst during the OER, giving rise to the performance degradation. This work suggests V4+ and its redox couple as a novel active component for the OER in metal-oxide electrocatalysts.

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Wu, Libo, Luo Yu, Xin Xiao, Fanghao Zhang, Shaowei Song, Shuo Chen, and Zhifeng Ren. "Recent Advances in Self-Supported Layered Double Hydroxides for Oxygen Evolution Reaction." Research 2020 (February 19, 2020): 1–17. http://dx.doi.org/10.34133/2020/3976278.

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Electrochemical water splitting driven by clean and sustainable energy sources to produce hydrogen is an efficient and environmentally friendly energy conversion technology. Water splitting involves hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in which OER is the limiting factor and has attracted extensive research interest in the past few years. Conventional noble-metal-based OER electrocatalysts like IrO2 and RuO2 suffer from the limitations of high cost and scarce availability. Developing innovative alternative nonnoble metal electrocatalysts with high catalytic activity and long-term durability to boost the OER process remains a significant challenge. Among all of the candidates for OER catalysis, self-supported layered double hydroxides (LDHs) have emerged as one of the most promising types of electrocatalysts due to their unique layered structures and high electrocatalytic activity. In this review, we summarize the recent progress on self-supported LDHs and highlight their electrochemical catalytic performance. Specifically, synthesis methods, structural and compositional parameters, and influential factors for optimizing OER performance are discussed in detail. Finally, the remaining challenges facing the development of self-supported LDHs are discussed and perspectives on their potential for use in industrial hydrogen production through water splitting are provided to suggest future research directions.

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Xu, Xiaopei, Haoxiang Xu, and Daojian Cheng. "Design of high-performance MoS2 edge supported single-metal atom bifunctional catalysts for overall water splitting via a simple equation." Nanoscale 11, no. 42 (2019): 20228–37. http://dx.doi.org/10.1039/c9nr06083a.

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Journal articles on the topic 'Oxygen Evolution Reaction (OER)'

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