Artykuły w czasopismach: „Oxygen Electrocatalysts”

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Jiang, Minhua, Xiaofang Yu, Haoqi Yang i Shuiliang Chen. "Optimization Strategies of Preparation of Biomass-Derived Carbon Electrocatalyst for Boosting Oxygen Reduction Reaction: A Minireview". Catalysts 10, nr 12 (16.12.2020): 1472. http://dx.doi.org/10.3390/catal10121472.

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Oxygen reduction reaction (ORR) has attracted considerable attention for clean energy conversion technologies to reduce traditional fossil fuel consumption and greenhouse gas emissions. Although platinum (Pt) metal is currently used as an electrocatalyst to accelerate sluggish ORR kinetics, the scarce resource and high cost still restrict its further scale-up applications. In this regard, biomass-derived carbon electrocatalysts have been widely adopted for ORR electrocatalysis in recent years owing to their tunable physical/chemical properties and cost-effective precursors. In this minireview, recent advances of the optimization strategies in biomass-derived carbon electrocatalysts towards ORR have been summarized, mainly focusing on the optimization of pore structure and active site. Besides, some current challenges and future perspectives of biomass-derived carbon as high-performance electrocatalysts for ORR have been also discussed in detail. Hopefully, this minireview will afford a guideline for better design of biomass-derived carbon electrocatalysts for ORR-related applications.

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Qin, Xupeng, Oluwafunmilola Ola, Jianyong Zhao, Zanhe Yang, Santosh K. Tiwari, Nannan Wang i Yanqiu Zhu. "Recent Progress in Graphene-Based Electrocatalysts for Hydrogen Evolution Reaction". Nanomaterials 12, nr 11 (25.05.2022): 1806. http://dx.doi.org/10.3390/nano12111806.

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Hydrogen is regarded as a key renewable energy source to meet future energy demands. Moreover, graphene and its derivatives have many advantages, including high electronic conductivity, controllable morphology, and eco-friendliness, etc., which show great promise for electrocatalytic splitting of water to produce hydrogen. This review article highlights recent advances in the synthesis and the applications of graphene-based supported electrocatalysts in hydrogen evolution reaction (HER). Herein, powder-based and self-supporting three-dimensional (3D) electrocatalysts with doped or undoped heteroatom graphene are highlighted. Quantum dot catalysts such as carbon quantum dots, graphene quantum dots, and fullerenes are also included. Different strategies to tune and improve the structural properties and performance of HER electrocatalysts by defect engineering through synthetic approaches are discussed. The relationship between each graphene-based HER electrocatalyst is highlighted. Apart from HER electrocatalysis, the latest advances in water electrolysis by bifunctional oxygen evolution reaction (OER) and HER performed by multi-doped graphene-based electrocatalysts are also considered. This comprehensive review identifies rational strategies to direct the design and synthesis of high-performance graphene-based electrocatalysts for green and sustainable applications.

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Liu, Huimin, Xinning Huang, Zhenjie Lu, Tao Wang, Yaming Zhu, Junxia Cheng, Yue Wang i in. "Trace metals dramatically boost oxygen electrocatalysis of N-doped coal-derived carbon for zinc–air batteries". Nanoscale 12, nr 17 (2020): 9628–39. http://dx.doi.org/10.1039/c9nr10800a.

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The commercialization of metal–air batteries requires efficient, low-cost, and stable bifunctional electrocatalysts for reversible electrocatalysis of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER).

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Cepitis, Ritums, Nadezda Kongi, Vitali Grozovski, Vladislav Ivaništšev i Enn Lust. "Multifunctional Electrocatalysis on Single-Site Metal Catalysts: A Computational Perspective". Catalysts 11, nr 10 (27.09.2021): 1165. http://dx.doi.org/10.3390/catal11101165.

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Multifunctional electrocatalysts are vastly sought for their applications in water splitting electrolyzers, metal-air batteries, and regenerative fuel cells because of their ability to catalyze multiple reactions such as hydrogen evolution, oxygen evolution, and oxygen reduction reactions. More specifically, the application of single-atom electrocatalyst in multifunctional catalysis is a promising approach to ensure good atomic efficiency, tunability and additionally benefits simple theoretical treatment. In this review, we provide insights into the variety of single-site metal catalysts and their identification. We also summarize the recent advancements in computational modeling of multifunctional electrocatalysis on single-site catalysts. Furthermore, we explain each modeling step with open-source-based working examples of a standard computational approach.

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Cherevko, Serhiy, Konrad Ehelebe, Daniel Escalera López, Julius Knöppel, YuPing Ku i Maja Milosevic. "(Invited) Electrocatalysts Dissolution Assessment in Fuel Cell and Water Electrolysis Research". ECS Meeting Abstracts MA2022-01, nr 49 (7.07.2022): 2052. http://dx.doi.org/10.1149/ma2022-01492052mtgabs.

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Durability and degradation are in the focus of modern electrocatalysis research. Before moving to real applications, e.g. fuel cells in transportation or water electrolyzers for production of green hydrogen, novel electrocatalytic materials must prove acceptable stability, but “how to test the stability of electrocatalysts”? In the relatively mature proton exchange membrane fuel cell (PEMFC) research, stability is evaluated using various accelerated stress tests (ASTs). Unfortunately, even for the most studied Pt/C electrocatalysts, degradation processes like carbon corrosion and Pt dissolution that occur during common ASTs are not easily distinguishable [1]. Moreover, advanced electrocatalysts such as different shape-controlled Pt alloy nanostructures, showing promising stability in ASTs performed in model aqueous systems, are often rendered useless when moved to real applications [2]. Catalysts free of platinum-group-metals, e.g. FeNC, demonstrate different degradation extents if tested in oxygen or argon [3]. Iridium oxides, the state of the art oxygen evolution reaction (OER) electrocatalysts, are prone to dissolution in aqueous media but much more stable in solid electrolyte based electrolyzers [4]. These examples demonstrate the need for rethinking current approaches to test electrocatalyst stability. This work highlights our recent results on using coupled electrochemical techniques and tuned gas diffusion electrode (GDE) and membrane electrode assembly (MEA) cells in fuel cell and water electrolysis research. It shows that by hyphenating GDE with inductively coupled plasma mass spectrometry (ICP-MS) it is possible to investigate dissolution of electrocatalysts, such as Pt/C for PEMFC and Fe-N-C for anion exchange membrane fuel cells (AEMFC), in-operando at conditions closely resembling those in real devices [5, 6]. As another representative example, the use of model MEAs to address the discrepancy of Ir dissolution in aqueous and solid polymer electrolytes is given [7]. Based on these examples, new strategies to test and understand electrocatalysts’ degradation are discussed. References: [1] E. Pizzutilo et al., On the need of improved accelerated degradation protocols (ADPs): Examination of platinum dissolution and carbon corrosion in half-cell tests, J. Electrochem. Soc., 163 (2016) F1510-F1514. [2] K. Kodama et al., Challenges in applying highly active Pt-based nanostructured catalysts for oxygen reduction reactions to fuel cell vehicles, Nature Nanotechnology, 16 (2021) 140-147. [3] K. Kumar et al., On the influence of oxygen on the degradation of Fe-N-C catalysts, Angew. Chem. Int. Ed., 59 (2020) 3235-3243. [4] S. Geiger et al., The stability number as a metric for electrocatalyst stability benchmarking, Nature Catalysis, 1 (2018) 508-515. [5] K. Ehelebe et al., Platinum dissolution in realistic fuel cell catalyst layers, Angew. Chem. Int. Ed., 60 (2021) 8882-8888. [6] Y.-P. Ku et al., Oxygen reduction reaction causes iron leaching from Fe-N-C electrocatalysts, (2021) Submitted, DOI: 10.21203/rs.3.rs-1171081/v1. [7] J. Knöppel et al., On the limitations in assessing stability of oxygen evolution catalysts using aqueous model electrochemical cells, Nature Communications 12 (2021) 2231.

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Gao, Xiaolan, i Ge Li. "Ultrasmall Co₉S₈nanocrystals on Carbon Nanoplates for Efficient Bifunctional Oxygen Electrocatalysis". ECS Meeting Abstracts MA2022-01, nr 49 (7.07.2022): 2074. http://dx.doi.org/10.1149/ma2022-01492074mtgabs.

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Electrochemical energy storage and conversion technologies based on electrocatalysis have been attracting more and more attention addressing increasing concerns on fossil fuel crisis and environmental deterioration. Fuel cells, zinc-air batteries, and water electrolyzer are believed to be promising candidates due to the environmental friendliness and high efficiency. These systems are associated with key reactions including oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Due to slow kinetics of these reactions, efficient electrocatalysts, e.g., Pt for ORR and RuOx/IrOx for OER, are usually required to overcome the energy barrier in electrochemical reactions to increase the reaction rate. However, the most advanced electrocatalysts are still based on above-mentioned noble metals with high cost and scarcity, which inevitably retards the large-scale commercialization of these noble metal-based energy systems. It is of great significance to replace noble metal catalysts with earth-abundant, cost-effective, and highly efficient catalysts. Here, we reported the controlled synthesis of ultrafine Co9S8 nanocrystals embedded in N, S-codoped multilayer-assembled carbon nanoplates (Co9S8/NSCP) for highly efficient oxygen electrocatalysis. The bifunctional Co9S8/NSCP electrocatalyst displays a high half-wave potential for ORR, and a low overpotential for OER in 0.1M KOH at a current density of 10 mA cm -2, much better than those of single component counterparts (Co9S8 or carbon) and comparable to noble metal catalysts. The high performance of Co9S8/NSCP can be attributed to the rationally designed hierarchical architecture with nanosized Co9S8 nanocrystals, rich N, S-codopants, highly exposed surface area, and protective graphitic layers, providing abundant active sites with full utilization and stable carbon support towards fast catalytic kinetics and durability. This work will promote further research on the development of highly efficient and stable non-noble metal electrocatalysts for ORR and OER.

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Madan, Chetna, i Aditi Halder. "Nonprecious Multi-Principal Metal Systems As the Air Electrode for a Solid-State Rechargeable Zinc-Air Battery". ECS Meeting Abstracts MA2022-02, nr 64 (9.10.2022): 2327. http://dx.doi.org/10.1149/ma2022-02642327mtgabs.

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Zinc-air battery technology is gaining recognition as a promising energy storage device to be used in portable electronics and electric vehicles. Despite possessing high theoretical energy density, environmental and operational safety, and easy accessibility of zinc reservoirs, the successful commercialization of zinc-air batteries suffers due to the poor oxygen electrocatalysis kinetics at the air cathode. The kinetically inept oxygen reduction and oxygen evolution reactions at the cathode lead to a large overpotential barrier and poor charge-discharge cyclic performance of the rechargeable zinc-air battery. This work demonstrates designing a multi-principal metal bifunctional electrocatalyst that is directly deposited on conductive, porous, and flexible substrates to eliminate the necessity of polymeric binders. The flexible bifunctional oxygen electrocatalyst used for the cathode of solid-state ZAB is assembled with gel polymer electrolyte and zinc anode giving excellent charge-discharge cyclic stability and constant discharge voltage (close to 1.65 V). These multi-principal metal electrocatalysts constituting quasi-equimolar concentration, provide numerous combinations of surface functionality, multiple adsorption sites, and electronic environments thus enabling better optimization of the catalytic performance.

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Wang, Chengcheng, Bingxue Hou, Xintao Wang, Zhan Yu, Dawei Luo, Mortaza Gholizadeh i Xincan Fan. "High-Performance A-Site Deficient Perovskite Electrocatalyst for Rechargeable Zn–Air Battery". Catalysts 12, nr 7 (27.06.2022): 703. http://dx.doi.org/10.3390/catal12070703.

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Zinc–air batteries are one of the most excellent of the next generation energy devices. However, their application is greatly hampered by the slow kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) of air electrode. It is of great importance to develop good oxygen electrocatalysts with long durability as well as low cost. Here, A-site deficient (SmSr)0.95Co0.9Pt0.1O3 perovskites have been studied as potential OER electrocatalysts prepared by EDTA–citrate acid complexing method. OER electrocatalytic performance of (SmSr)0.95Co0.9Pt0.1O3 was also evaluated. (SmSr)0.95Co0.9Pt0.1O3 electrocatalysts exhibited good OER activities in 0.1 M KOH with onset potential and Tafel slope of 1.50 V and 87 mV dec−1, similar to that of Ba0.5Sr0.5Co0.8Fe0.2O3 (BSCF-5582). Assembled rechargeable Zn–air batteries exhibited good discharge potential and charge potential with high stability, respectively. Overall, all results illustrated that (SmSr)0.95Co0.9Pt0.1O3 is an excellent OER electrocatalyst for zinc–air batteries. Additionally, this work opens a good way to synthesize highly efficient electrocatalysts from A-site deficient perovskites.

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Tariq, Irsa, Muhammad Adeel Asghar, Abid Ali, Amin Badshah, Syed Mustansar Abbas, Waheed Iqbal, Muhammad Zubair, Ali Haider i Shahid Zaman. "Surface Reconstruction of Cobalt-Based Polyoxometalate and CNT Fiber Composite for Efficient Oxygen Evolution Reaction". Catalysts 12, nr 10 (15.10.2022): 1242. http://dx.doi.org/10.3390/catal12101242.

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Polyoxometalates (POMs), as carbon-free metal-oxo-clusters with unique structural properties, are emerging water-splitting electrocatalysts. Herein, we explore the development of cobalt-containing polyoxometalate immobilized over the carbon nanotube fiber (CNTF) (Co4POM@CNTF) towards efficient electrochemical oxygen evolution reaction (OER). CNTF serves as an excellent electron mediator and highly conductive support, while the self-activation of the part of Co4POM through restructuring in basic media generates cobalt oxides and/or hydroxides that serve as catalytic sites for OER. A modified electrode fabricated through the drop-casting method followed by thermal treatment showed higher OER activity and enhanced stability in alkaline media. Furthermore, advanced physical characterization and electrochemical results demonstrate efficient charge transfer kinetics and high OER performance in terms of low overpotential, small Tafel slope, and good stability over an extended reaction time. The significantly high activity and stability achieved can be ascribed to the efficient electron transfer and highly electrochemically active surface area (ECSA) of the self-activated electrocatalyst immobilized over the highly conductive CNTF. This research is expected to pave the way for developing POM-based electrocatalysts for oxygen electrocatalysis.

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Ni, Chunsheng, Shuntian Huang, Tete Daniel Koudama, Xiaodong Wu, Sheng Cui, Xiaodong Shen i Xiangbao Chen. "Tuning the Electronic Structure of a Novel 3D Architectured Co-N-C Aerogel to Enhance Oxygen Evolution Reaction Activity". Gels 9, nr 4 (7.04.2023): 313. http://dx.doi.org/10.3390/gels9040313.

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Hydrogen generation through water electrolysis is an efficient technique for hydrogen production, but the expensive price and scarcity of noble metal electrocatalysts hinder its large-scale application. Herein, cobalt-anchored nitrogen-doped graphene aerogel electrocatalysts (Co-N-C) for oxygen evolution reaction (OER) are prepared by simple chemical reduction and vacuum freeze-drying. The Co (0.5 wt%)-N (1 wt%)-C aerogel electrocatalyst has an optimal overpotential (0.383 V at 10 mA/cm2), which is significantly superior to that of a series of M-N-C aerogel electrocatalysts prepared by a similar route (M = Mn, Fe, Ni, Pt, Au, etc.) and other Co-N-C electrocatalysts that have been reported. In addition, the Co-N-C aerogel electrocatalyst has a small Tafel slope (95 mV/dec), a large electrochemical surface area (9.52 cm2), and excellent stability. Notably, the overpotential of Co-N-C aerogel electrocatalyst at a current density of 20 mA/cm2 is even superior to that of the commercial RuO2. In addition, density functional theory (DFT) confirms that the metal activity trend is Co-N-C > Fe-N-C > Ni-N-C, which is consistent with the OER activity results. The resulting Co-N-C aerogels can be considered one of the most promising electrocatalysts for energy storage and energy saving due to their simple preparation route, abundant raw materials, and superior electrocatalytic performance.

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Hung, Sung-Fu. "In-situ X-ray techniques for non-noble electrocatalysts". Pure and Applied Chemistry 92, nr 5 (26.05.2020): 733–49. http://dx.doi.org/10.1515/pac-2019-1006.

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AbstractElectrocatalysis offers an alternative solution for the energy crisis because it lowers the activation energy of reaction to produce economic fuels more accessible. Non-noble electrocatalysts have shown their capabilities to practical catalytic applications as compared to noble ones, whose scarcity and high price limit the development. However, the puzzling catalytic processes in non-noble electrocatalysts hinder their advancement. In-situ techniques allow us to unveil the mystery of electrocatalysis and boost the catalytic performances. Recently, various in-situ X-ray techniques have been rapidly developed, so that the whole picture of electrocatalysis becomes clear and explicit. In this review, the in-situ X-ray techniques exploring the structural evolution and chemical-state variation during electrocatalysis are summarized for mainly oxygen evolution reaction (OER), hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and carbon dioxide reduction reaction (CO2RR). These approaches include X-ray Absorption Spectroscopy (XAS), X-ray diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). The information seized from these in-situ X-ray techniques can effectively decipher the electrocatalysis and thus provide promising strategies for advancing the electrocatalysts. It is expected that this review could be conducive to understanding these in-situ X-ray approaches and, accordingly, the catalytic mechanism to better the electrocatalysis.

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Dong, Dongqi, Zexing Wu, Jie Wang, Gengtao Fu i Yawen Tang. "Recent progress in Co9S8-based materials for hydrogen and oxygen electrocatalysis". Journal of Materials Chemistry A 7, nr 27 (2019): 16068–88. http://dx.doi.org/10.1039/c9ta04972j.

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Co₉S₈-based materials have attracted tremendous attention owing to their unique physical properties, which are widely adopted as electrocatalysts in hydrogen- and oxygen-related electrocatalysis.

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Solangi, Muhammad Yameen, Abdul Hanan Samo, Abdul Jaleel Laghari, Umair Aftab, Muhammad Ishaque Abro i Muhammad Imran Irfan. "MnO2@Co3O4 nanocomposite based electrocatalyst for effective oxygen evolution reaction". Sukkur IBA Journal of Emerging Technologies 5, nr 1 (30.06.2022): 32–40. http://dx.doi.org/10.30537/sjet.v5i1.958.

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For large-scale energy applications, conceiving low-cost and simple earth-abundant electrocatalysts are more difficult. By using an aqueous chemical technique, MnO2 was added into Co3O4 with varying concentrations to prepare MnO2@Co3O4 nanocomposite (CM). In an aqueous solution of 1 M KOH, the electrocatalyst with a greater concentration of MnO2 outperforms in terms of OER. To confirm the composition, crystalline structure, and morphology of the electrocatalyst, analytical methods such as X-ray diffraction (XRD) techniques, Fourier transformed infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used. At 20 mA/cm2 current density, the electrocatalyst had a lowest overpotential of 310 mV verses Reversible hydrogen electrode (RHE). The CM-0.4 electrocatalyst has a small Tafel slope value and charge transfer resistance of approximately 72 mV/dec and 74 Ω which confirm its high catalytic activity. The electrocatalyst reveals a double layer capacitance (Rct) of 18 µF/cm2 and an electrochemical active surface area (ECSA) of 450 cm2, demonstrating that addition of MnO2 impurities into Co3O4 enhances the active catalyst sites. These findings contribute to the knowledge of these kind of catalysts, that will assist in the development of novel electrocatalysts which are feasible for prospective energy generation technologies.

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Das, Srijib, Souvik Ghosh, Tapas Kuila, Naresh Chandra Murmu i Aniruddha Kundu. "Biomass-Derived Advanced Carbon-Based Electrocatalysts for Oxygen Reduction Reaction". Biomass 2, nr 3 (15.08.2022): 155–77. http://dx.doi.org/10.3390/biomass2030010.

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Noble metal-based materials are enormously used as a cathode material for electrocatalytic oxygen reduction reaction (ORR), which plays an important role in determining the performance of energy conversion and storage devices such as fuel cells, metal-air battery, and so on. The practicability of these energy devices is mainly related to the cost of the cathodic ORR electrocatalyst. Hence, a cost-effective and environmentally benign approach is highly demanding to design the electrocatalyst for ORR and replacing noble metal-based electrocatalyst. In this regard, biomass-derived hierarchically porous carbon-based materials have become attractive options compared to metal-based electrocatalysts due to their several advantages such as abundance in nature, economic viability, characteristic sustainability, environmental friendliness, and excellent physicochemical properties. Moreover, harsh chemicals are not being involved during their synthesis, and they intrinsically possess a variety of heteroatoms (N, P, S, etc.), which are key for augmenting the electrocatalytic activity. In the present review article, the recent progress on biomass-derived cathode electrocatalysts has been summarized for ORR including a brief account of bioresource selection, synthesis methods, and processing criteria that greatly influences the electrocatalytic activity.

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Zhuang, Linzhou, Shiyi Li, Jiankun Li, Keyu Wang, Zeyu Guan, Chen Liang i Zhi Xu. "Recent Advances on Hydrogen Evolution and Oxygen Evolution Catalysts for Direct Seawater Splitting". Coatings 12, nr 5 (12.05.2022): 659. http://dx.doi.org/10.3390/coatings12050659.

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Producing hydrogen via water electrolysis could be a favorable technique for energy conversion, but the freshwater shortage would inevitably limit the industrial application of the electrolyzers. Being an inexhaustible resource of water on our planet, seawater can be a promising alternative electrolyte for industrial hydrogen production. However, many challenges are hindering the actual application of seawater splitting, especially the competing reactions relating to chlorine at the anode that could severely corrode the catalysts. The execution of direct seawater electrolysis needs efficient and robust electrocatalysts that can prevent the interference of competing reactions and resist different impurities. In recent years, researchers have made great advances in developing high-efficiency electrocatalysts with improved activity and stability. This review will provide the macroscopic understanding of direct seawater splitting, the strategies for rational electrocatalyst design, and the development prospects of hydrogen production via seawater splitting. The nonprecious metal-based electrocatalysts for stable seawater splitting and their catalytic mechanisms are emphasized to offer guidance for designing the efficient and robust electrocatalyst, so as to promote the production of green hydrogen via seawater splitting.

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Weng, Yu-Ching, Cheng-Jen Ho, Hui-Hsuan Chiao i Chen-Hao Wang. "Pt3Ni/C and Pt3Co/C cathodes as electrocatalysts for use in oxygen sensors and proton exchange membrane fuel cells". Zeitschrift für Naturforschung B 75, nr 12 (16.12.2020): 1029–35. http://dx.doi.org/10.1515/znb-2020-0116.

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AbstractThe composites Pt3Ni/C and Pt3Co/C are electrocatalysts for oxygen reduction reactions (ORRs). This study compares the electrocatalytic activity of these electrodes that are used to detect oxygen, and determines their suitability for use in proton exchange membrane fuel cells (PEMFCs). Chemical reduction is used to produce the Pt3Ni/C and Pt3Co/C electrocatalysts. The particle size, elemental composition and crystallinity of the intermetallic electrocatalysts are determined using transmission electron microscopy (TEM) and an energy-dispersive spectrometer (EDX). The ORR activity of the Pt3Ni/C and Pt3Co/C electrocatalysts is determined using cyclic voltammetry (CV), a polarization curve (PC) and a rotating disk electrode (RDE). The Pt3Ni/C electrode registers a greater current for the ORR as compared to the Pt3Co/C electrode. Both electrodes exhibit a linear relationship between response current and oxygen concentration in the detection range from 100 to 1000 ppm. The Pt3Ni/C electrode exhibits a significant sensitivity to oxygen up to 13.4 μA ppm−1 cm−2. A membrane electrode assembly (MEA) that is produced using Pt3Ni/C as a cathodic electrocatalyst in a single PEMFC generates a maximum power density of 1097 mW cm−2.

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Ma, Junchao, Boyan Lu, Sha Wang, Wenxiu He, Xiaojue Bai, Tieqiang Wang, Xuemin Zhang i in. "MOF-derived CuCoNi trimetallic hybrids as efficient oxygen evolution reaction electrocatalysts". New Journal of Chemistry 44, nr 6 (2020): 2459–64. http://dx.doi.org/10.1039/c9nj05562b.

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Wu, Hengbo, Jie Wang, Wei Jin i Zexing Wu. "Correction: Recent development of two-dimensional metal–organic framework derived electrocatalysts for hydrogen and oxygen electrocatalysis". Nanoscale 12, nr 43 (2020): 22340–48. http://dx.doi.org/10.1039/d0nr90231d.

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Correction for ‘Recent development of two-dimensional metal–organic framework derived electrocatalysts for hydrogen and oxygen electrocatalysis’ by Hengbo Wu et al., Nanoscale, 2020, 12, 18497–18522 DOI: 10.1039/D0NR04458J.

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Zhang, Meng, Wenjie Wu, Zhen Wang, Gang Xie i Xiaohui Guo. "Boosting Water Oxidation Activity via Carbon–Nitrogen Vacancies in NiFe Prussian Blue Analogue Electrocatalysts". Colloids and Interfaces 7, nr 1 (10.02.2023): 14. http://dx.doi.org/10.3390/colloids7010014.

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The development of electrocatalysts for oxygen evolution reactions (OERs) is of great significance for hydrogen production. Defect engineering is an effective strategy to improve the OER performance of electrocatalyst by regulating the local electronic and atomic structures of electrocatalysts. Here, we successfully synthesized defective Prussian blue analogues (PBAs) with rich CN vacancies (D-NiFe PBA) as efficient OER electrocatalysts. The optimized D-NiFe PBA exhibited an overpotential of 280 mV at 10 mA cm−2 and a superior stability for over 100 h in KOH electrolytes. The formation of CN vacancies in the NiFe PBA could effectively inhibit the loss of Fe active sites, promote the reconstruction of the NiFe oxygen (hydroxide) active layer in the OER process, and further improve the electrocatalytic activity and stability of the VCN-NiFe PBA. This work presents a feasible approach for the wide application of vacancy defects in PBA electrocatalysts.

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Jeon, Jaeeun, Kyoung Ryeol Park, Kang Min Kim, Daehyeon Ko, HyukSu Han, Nuri Oh, Sunghwan Yeo, Chisung Ahn i Sungwook Mhin. "CoFeS2@CoS2 Nanocubes Entangled with CNT for Efficient Bifunctional Performance for Oxygen Evolution and Oxygen Reduction Reactions". Nanomaterials 12, nr 6 (16.03.2022): 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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Marques, Inês S., Bruno Jarrais, Israël-Martyr Mbomekallé, Anne-Lucie Teillout, Pedro de Oliveira, Cristina Freire i Diana M. Fernandes. "Synergetic Effects of Mixed-Metal Polyoxometalates@Carbon-Based Composites as Electrocatalysts for the Oxygen Reduction and the Oxygen Evolution Reactions". Catalysts 12, nr 4 (14.04.2022): 440. http://dx.doi.org/10.3390/catal12040440.

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The smart choice of polyoxometalates (POMs) and the design of POM@carbon-based composites are promising tools for producing active electrocatalysts for both the oxygen reduction (ORR) and the oxygen evolution reactions (OER). Hence, herein, we report the preparation, characterization and application of three composites based on doped, multi-walled carbon nanotubes (MWCNT_N6) and three different POMs (Na12[(FeOH2)2Fe2(As2W15O56)2]·54H2O, Na12[(NiOH2)2Ni2(As2W15O56)2]·54H2O and Na14[(FeOH2)2Ni2(As2W15O56)2]·55H2O) as ORR and OER electrocatalysts in alkaline medium (pH = 13). Overall, the three POM@MWCNT_N6 composites showed good ORR performance with onset potentials between 0.80 and 0.81 V vs. RHE and diffusion-limiting current densities ranging from −3.19 to −3.66 mA cm−2. Fe4@MWCNT_N6 and Fe2Ni2@MWCNT_N6 also showed good stability after 12 h (84% and 80% of initial current). The number of electrons transferred per O2 molecule was close to three, suggesting a mixed regime. Moreover, the Fe2Ni2@MWCNT_N6 presented remarkable OER performance with an overpotential of 0.36 V vs. RHE (for j = 10 mA cm−2), a jmax close to 135 mA cm−2 and fast kinetics with a Tafel slope of 45 mV dec−1. More importantly, this electrocatalyst outperformed not only most POM@carbon-based composites reported so far but also the state-of-the-art RuO2 electrocatalyst. Thus, this work represents a step forward towards bifunctional electrocatalysts using less expensive materials.

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Zheng, Penglun, Quanyi Liu, Xiaoliang Peng, Laiquan Li i Jun Yang. "Constructing Ni–Mo2C Nanohybrids Anchoring on Highly Porous Carbon Nanotubes as Efficient Multifunctional Electrocatalysts". Nano 15, nr 10 (październik 2020): 2050135. http://dx.doi.org/10.1142/s1793292020501350.

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It is important for regenerative fuel cells, rechargeable metal–air batteries and water splitting to find reasonable designed nonprecious metal catalysts, which have efficient and durable electrocatalytic activities for oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In this work, through a simple hydrothermal method and following annealing process, Mo2C and Ni nanoparticles were encapsulated in a nanoporous hierarchical structure of carbon (Ni/Mo2C/C). The ingenious structure delivers several favorable characteristics including abundant active sites resulting from hollow and mesoporous architecture, boosted reaction kinetics from metallic components, sufficient interfacial effect and synergistic effect from intimate integration of Mo2C, Ni and C. The multifunctional Ni/Mo2C/C hybrid electrocatalyst performs excellently for ORR, OER and HER, better than most of the reported electrocatalysts with three functions. A facile and novel strategy was developed to construct the multifunctional catalysts with excellent electrocatalysis behavior.

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Manivannan, Natarajan, Vijai Shankar Balachandran i V. S. Vasantha. "Carbon Supported Platinum-Molybdenum Alloy Nanoparticles for Oxygen Reduction Reaction". Asian Journal of Chemistry 33, nr 5 (2021): 1153–58. http://dx.doi.org/10.14233/ajchem.2021.23165.

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Fuel cells are gaining importance in the emerging area of power generation. However, sluggishness of the cathodic oxygen reduction reaction (ORR) and usage of expensive electrocatalysts are hindering its widespread application. Hence, an effort has been made in the present study to synthesize efficient electrocatalysts based on Pt-Mo alloys with varying atomic ratios (0-100 at. %) by thermal decomposition method. The synthesized samples were characterized using XRD, SEM, TEM and XPS techniques. The electrocatalytic activity for ORR was measured using cyclic voltammetry and rotating disk electrode for all the samples and Pt-Mo (1:1) electrocatalyst performed better among the synthesized electrocatalysts with ORR current density of 63 mA/cm2 at an applied potential of 0.6 V vs. Hg/HgSO4. The present study suggests that Pt-Mo studied are proven to be a superior catalyst than a costly Pt catalyst with high ORR activity.

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Liu, Yong, Tao Wang, Guo Gong i Yong Zhang. "Highly Nitrogen-Doped Porous Carbon Nanosheets Electrocatalyst from Ethylenediaminetetraacetic Acid Ferric Sodium Salt for Oxygen Reduction Reaction". Nanoscience and Nanotechnology Letters 12, nr 3 (1.03.2020): 317–23. http://dx.doi.org/10.1166/nnl.2020.3108.

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Fuel cells have the great prospect in energy storage technology from the perspective of energy conservation and ecological protection. However, oxygen reduction reaction (ORR) always proceeds sluggishly leads to limited performance. Choosing an excellent ORR electrocatalyst is considered to be an effective strategy. Herein, we have presented an easy synthesis method to prepare highly nitrogen-doped porous carbon nanosheets (HNPC) electrocatalysts. The as-synthesized HNPC electrocatalysts delivered excellent catalytic properties by 4e– transfer pathway with extremely few HO2–, due to excellent compositional characteristics (highly N doping) and structural features (porosity). It provides some guidance for the synthesis of excellent electrocatalysts, which will have certain significance for the development of fuel cells.

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Pharkya, Pallavi, Akram Alfantazi i Zoheir Farhat. "Fabrication Using High-Energy Ball-Milling Technique and Characterization of Pt-Co Electrocatalysts for Oxygen Reduction in Polymer Electrolyte Fuel Cells". Journal of Fuel Cell Science and Technology 2, nr 3 (2.02.2005): 171–78. http://dx.doi.org/10.1115/1.1895985.

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This work discusses the fabrication and characterization of Pt-Co electrocatalysts for polymer electrolyte membrane fuel cells (PEMFC) and electrocatalysis of the oxygen reduction reaction. Two sets of carbon supported catalysts with Pt:Co in the atomic ratio of 0.25:0.75 and 0.75:0.25 were prepared using a high-energy ball-milling technique. One of the Pt-Co electrocatalysts was subjected to lixiviation to examine the change in surface area. Microstructural characterization of the electrocatalysts was done using scanning electron microscopy, transmission electron microscopy, x-ray diffractometry, and x-ray photoelectron spectroscopy. Electrochemical characterization of the electrocatalysts was done in acidic and alkaline media using cyclic voltammetry and potentiodynamic polarization techniques. These tests were performed at room and higher temperature (50°C). Performances of the electrocatalysts were also compared with the commercial E-TEK Pt:Co alloy electrocatalysts of the compositions 10% Pt-Co alloy (1:1 a/o) and 40% Pt-Co alloy (1:1 a/o) on Vulcan XC-72.

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Wang, Quan, Baosen Mi, Jun Zhou, Ziwei Qin, Zhuo Chen i Hongbin Wang. "Hollow-Structure Pt-Ni Nanoparticle Electrocatalysts for Oxygen Reduction Reaction". Molecules 27, nr 8 (14.04.2022): 2524. http://dx.doi.org/10.3390/molecules27082524.

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An electrocatalyst with high oxygen reduction reaction (ORR) activity and high stability during start–stop operation is necessary. In this paper, hollow-structure Pt-Ni electrocatalysts are investigated as ORR catalysts. After synthesis via sacrificial SiO2 template method, the electrocatalyst exhibits much higher specific activity (1.88 mA/cm2) than a commercial Pt/C catalyst. The mass activity (0.49 A/mg) is 7 times higher than the commercial Pt/C catalyst. The kinetics of the ORR is evaluated using Tafel and K-L plots. It also exhibits a higher durability than commercial Pt/C catalyst during accelerated durability test (ADT). Moreover, the electrocatalyst shows good resistance against accelerated durability test for start–stop, the specific activity and mass activity drops 34.6% and 40.8%, respectively, far better than the commercial catalyst.

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Albiter, Luis A., Kathleen O. Bailey, Jose Fernando Godinez Salomon i Christopher P. Rhodes. "Ruthenium-Zirconium Oxides As Highly Stable Oxygen Evolution Electrocatalysts". ECS Meeting Abstracts MA2022-02, nr 44 (9.10.2022): 1648. http://dx.doi.org/10.1149/ma2022-02441648mtgabs.

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The further development and utilization of proton exchange membrane water electrolyzers (PEMWEs) is hindered by the cost, activity, and stability of the oxygen evolution reaction (OER) electrocatalyst. Iridium oxide (IrOx) is currently the go-to OER electrocatalyst, as it has been shown to have relative high activity and stability when compared to other OER active catalysts. However, iridium is one of the rarest elements in the Earth’s crust and therefore cost is a major limitation of iridium-based electrocatalysts. Ruthenium oxide (RuO2) is a highly active OER catalyst; although, it is highly unstable in acidic media and undergoes catalyst degradation over time. We investigated modifying RuO2 by substituting zirconium, which is highly stable in acidic conditions, to provide an electrocatalyst with increased stability. Our study explored the effect of low and moderate zirconium concentrations within RuO2 (Ru1-xZrxO2) on the structure, morphology, OER activity, and stability. The structure and morphology were characterized by X-ray diffraction and scanning electron microscopy. Preliminary results from XRD showed no observable phase separation at low Zr concentrations, and peak shifts were indicative of the incorporation of the larger Zr ion into the crystal structure of rutile RuO2. The OER activities and stabilities of Ru1-xZrxO2 were measured using a rotating disk electrode configuration and compared with RuO2. Our preliminary results show that the OER activity and stability are strongly affected by the addition of Zr and there may be an optimal concentration range for obtaining a balance between OER activity and stability. Our work furthers the understanding of how to develop OER electrocatalysts with increased stability while maintaining a high OER activity, which is crucial to the large-scale adoption of PEMWE’s.

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Gaolatlhe, Lesego, Augustus Kelechi Lebechi, Aderemi Bashiru Haruna, Thapelo Prince Mofokeng, Patrick Vaati Mwonga i Kenneth Ikechukwu Ozoemena. "High Entropy Spinel Oxide As a Bifunctional Electrocatalyst for Rechargeable Zinc-Air Battery". ECS Meeting Abstracts MA2022-02, nr 7 (9.10.2022): 2419. http://dx.doi.org/10.1149/ma2022-0272419mtgabs.

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Rechargeable zinc-air battery (RZAB) represents one of the ‘beyond-the-lithium-ion’ battery technologies with great potential for renewable energy storage. It is safe, environmentally benign, and excellent potential for affordable applications in resource-limited countries, ranging from residential and industrial electricity supply, transport (e.g., electric vehicles) to mobile and consumer electronics markets. RZABs possess high theoretical specific energy density of 1086 Wh/kg, which is 5 times greater than that of the conventional lithium-ion battery (LIB). The key challenge that conspires against the widespread commercialization of RZAB is the sluggish oxygen reaction kinetics that impedes reversibility of the system. Thus, it has become quite critical to develop low-cost and high-performance bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) [1,2]. High entropy materials (HEMs) have emerged as electrocatalysts for ORR and OER. HEMs contain five or more metals in equal proportions. Their unique conformational entropy and physico-chemical properties (including lattice distortion, synergistic effects amongst the different metals, and rich defect chemistries) promise to improve the kinetics of ORR / OER and electrochemical cycling stability. In this work, the high entropy spinel oxide, (CoCuFeMnNi)3O4 supported on conductive carbon has been synthesized and characterised using XRD, XPS, HRTEM, SEM and others. Preliminary electrochemistry shows improved ORR/OER kinetics. This presentation will discuss the performance of the initial lab-based RZAB using this electrocatalyst. References AB Haruna and KI Ozoemena, Manganese-based bifunctional electrocatalysts for zinc-air batteries, Opin. Electrochem. 2020, 21, 219-224 AK Ipadeola, AB Haruna, L Gaolatlhe, AK Lebechi, J Meng, QQ Pang, K Eid, AM Abdullah, and KI Ozoemena, Efforts at Enhancing Bifunctional Electrocatalysis and Related Events for Rechargeable Zinc-Air Batteries; ChemElectroChem 2021, 8, 3998-4018

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Zhang, Huiyi, Yan Wang, Daqi Song, Liang Wang, Yifan Zhang i Yong Wang. "Cerium-Based Electrocatalysts for Oxygen Evolution/Reduction Reactions: Progress and Perspectives". Nanomaterials 13, nr 13 (23.06.2023): 1921. http://dx.doi.org/10.3390/nano13131921.

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Ce-based materials have been widely used in photocatalysis and other fields because of their rich redox pairs and oxygen vacancies, despite research on the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) remaining scare. However, most pristine cerium-based materials, such as CeO2, are non-conductive materials. Therefore, how to obtain highly conductive and stable OER/ORR electrocatalysts is currently a hot research topic. To overcome these limitations, researchers have proposed a variety of strategies to promote the development of Ce-based electrocatalysts in recent years. This progress report focuses on reviewing new strategies concerning three categories of Ce-based electrocatalysts: metal–organic framework (MOF) derivatives, structure tuning, and polymetallic doping. It also puts forward the main existing problems and future prospects. The content of cerium in the crust is about 0.0046%, which is the highest among the rare earth elements. As a low-cost rare earth material, Ce-based materials have a bright future in the field of electrocatalysis due to replacing precious metal and some transition metals.

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Nagajyothi, Patnamsetty Chidanandha, Krishnapuram Pavani, Rajavaram Ramaraghavulu i Jaesool Shim. "Ce–Metal–Organic Framework-Derived CeO2–GO: An Efficient Electrocatalyst for Oxygen Evolution Reaction". Inorganics 11, nr 4 (11.04.2023): 161. http://dx.doi.org/10.3390/inorganics11040161.

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The oxygen evolution reaction (OER) is a crucial half-reaction in water splitting. However, this reaction is kinetically sluggish owing to the four-electron (4 e−) transfer process. Therefore, the development of low-cost, stable, highly efficient, and earth-abundant electrocatalysts for the OER is highly desirable. Metal oxides derived from metal–organic frameworks (MOFs) are among the most efficient electrocatalysts for the OER. Herein, Ce–MOF-derived CeO2/graphene oxide (GO) composites were successfully prepared using a facile method. The composites with 0, 25, 50, and 100 mg GO were named CeO2, CeO2–GO-1, CeO2–GO-2, and CeO2–GO-3, respectively. The physicochemical characteristics of the electrocatalysts were assessed using several analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis. The TEM results revealed that the CeO2 had a sheet-like morphology and that a GO layer was noticeable in the synthesized CeO2–GO-3 composite. The characterization results confirmed the formation of impurity-free CeO2–GO composites. The OER activity and stability were measured using cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The CeO2–GO-3 electrocatalyst has a smaller Tafel slope (176 mV·dec−1) and lower overpotential (240 mV) than the other electrocatalysts. In addition, it exhibited high cyclic stability for up to 10 h. Therefore, the inexpensive CeO2–GO-3 electrocatalyst is a promising OER candidate.

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Tang, Chaoyun, Tewodros Asefa i Nianqiang Wu. "Metal-Coordinated Hydrogels As Efficient Oxygen Evolution Electrocatalysts". ECS Meeting Abstracts MA2022-02, nr 48 (9.10.2022): 1798. http://dx.doi.org/10.1149/ma2022-02481798mtgabs.

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Conductive polymer hydrogels have large surface area and high conductivity. Their properties can easily be tailored further by functionalizing them with metals and nonmetals. However, the potential of metal-conjugated hydrogels for electrocatalysis has rarely been investigated. In this work, we report the synthesis of transition metals-conjugated polyaniline-phytic acid (PANI-PA) hydrogels that show efficient electrocatalytic properties for the oxygen evolution reaction (OER). Among many transition metals studied, Fe is accommodated by the hydrogel the most because of the favorable affinity of the PA groups in the hydrogel for Fe. Meanwhile, those containing both Fe and Co are found to be the most effective for electrocatalysis of OER. The most optimized such hydrogel, NF@Hgel-Fe0.3Co0.1, which has 3:1 ratio of Fe and Co, needs an overpotential of only 280 mV to catalyze OER with a current density of 10 mV cm-2 in 1 M KOH solution. Furthermore, these metal-doped PANI-PA hydrogels can easily be loaded on nickel foam and carbon cloth via a simple soak-and-dry method to form free-standing electrodes. Overall, the work demonstrates a facile synthesis and fabrication of sustainable OER electrocatalysts and electrodes that are composed of easily processable hydrogels conjugated with various earth-abundant transition metals. Figure R. Schematic illustration of the synthesis of PA-PANI-Metal (Hgel-M x ) hydrogels for electrocatalysis of OER. Figure 1

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Ding, Xiaoteng, Wei Cui, Xiaohua Zhu, Jianwei Zhang i Yusheng Niu. "Intrinsic poorly-crystallized Fe5O7(OH)·4H2O: a highly efficient oxygen evolution reaction electrocatalyst under alkaline conditions". RSC Advances 9, nr 72 (2019): 42470–73. http://dx.doi.org/10.1039/c9ra06374a.

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A novel low-crystallized Fe₅O₇(OH)·4H₂O electrocatalyst was fabricated and it demonstrates excellent OER activity, outperforming most of the reported Fe-based electrocatalysts.

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Kim, Myeong Gyu, i Yun-Hyuk Choi. "Electrocatalytic Properties of Co3O4 Prepared on Carbon Fibers by Thermal Metal–Organic Deposition for the Oxygen Evolution Reaction in Alkaline Water Electrolysis". Nanomaterials 13, nr 6 (12.03.2023): 1021. http://dx.doi.org/10.3390/nano13061021.

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Cobalt oxide (Co3O4) serves as a promising electrocatalyst for oxygen evolution reactions (OER) in water-electrolytic hydrogen production. For more practical applications, advances in dry-deposition processes for the high-throughput fabrication of such Co3O4 electrocatalysts are needed. In this work, a thermal metal–organic deposition (MOD) technique is developed to form Co3O4 deposits on microscale-diameter carbon fibers constituting a carbon fiber paper (CFP) substrate for high-efficiency OER electrocatalyst applications. The Co3O4 electrocatalysts are deposited while uniformly covering the surface of individual carbon fibers in the reaction temperature range from 400 to 800 °C under an ambient Ar atmosphere. It is found that the microstructure of deposits is dependent on the reaction temperature. The Co3O4 electrocatalysts prepared at 500 °C and over exhibit values of 355–384 mV in overpotential (η10) required to reach a current density of 10 mA cm−2 and 70–79 mV dec−1 in Tafel slope, measured in 1 M KOH aqueous solution. As a result, it is highlighted that the improved crystallinity of the Co3O4 electrocatalyst with the increased reaction temperature leads to an enhancement in electrode-level OER activity with the high electrochemically active surface area (ECSA), low charge transfer resistance (Rct), and low η10, due to the enhanced electrical conductivity. On the other hand, it is found that the inherent catalytic activity of the surface sites of the Co3O4, represented by the turnover frequency (TOF), decreases with reaction temperature due to the high-temperature sintering effect. This work provides the groundwork for the high-throughput fabrication and rational design of high-performance electrocatalysts.

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Jeon, In Yup, i Jong Beom Baek. "Iodinated Charcoal as Electrocatalyst for Oxygen Reduction Reaction". Applied Mechanics and Materials 749 (kwiecień 2015): 36–40. http://dx.doi.org/10.4028/www.scientific.net/amm.749.36.

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Large quantity of iodinated charcoal (I-AC) is firstly prepared by simple ball-milling activated chargoalin the presence of iodine. The resultant I-AC contains iodine of 0.59 at.% (EDS) and shows that the morphology is changed from random powder into flake-like platelet. It is uased as electrocatalyst for oxygen reduction reaction (ORR), exhibiting outstanding electrocatalytic activities with higher selectivity, better tolerance to methanol crossover than those of the starting AC and commercial Pt/C electrocatalysts.

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Kim, Jihun, Dae Hoon Lee, Yang Yang, Kai Chen, Chunli Liu, Jun Kang i Oi Lun Li. "Hybrid Molybdenum Carbide/Heteroatom-Doped Carbon Electrocatalyst for Advanced Oxygen Evolution Reaction in Hydrogen Production". Catalysts 10, nr 11 (8.11.2020): 1290. http://dx.doi.org/10.3390/catal10111290.

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Hydrogen energy is one of the key technologies that can help to prevent global warming. A water electrolysis process can be used to produce hydrogen, in which hydrogen is produced at one electrode of the electrochemical cell, and oxygen is produced at the other electrode. On the other hand, the oxygen evolution reaction (OER) requires multiple reaction steps and precious-metal-based catalysts (e.g., Ru/C, Ir/C, RuO2, and IrO2) as electrocatalysts to improve the reaction rate. Their high cost and limited supply, however, limit their applications to the mass production of hydrogen. In this study, boron, nitrogen-doped carbon incorporated with molybdenum carbide (MoC-BN/C) was synthesized to replace the precious-metal-based catalysts in the OER. B, N-doped carbon with nanosized molybdenum nanoparticles was fabricated by plasma engineering. The synthesized catalysts were heat-treated at 600, 700, and 800 °C in nitrogen for one hour to enhance the conductivity. The best MoC-BN/C electrocatalysts (heated at 800 °C) exhibited superior OER catalytic activity: 1.498 V (vs. RHE) and 1.550 V at a current density of 10 and 100 mA/cm2, respectively. The hybrid electrocatalysts even outperformed the noble electrocatalyst (5 wt.% Ru/C) with higher stability. Therefore, the hybrid electrocatalyst can replace expensive precious-metal-based catalysts for the upcoming hydrogen economy.

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He, Yan, Tao Yu, Hui Wen i Rui Guo. "Boosting the charge transfer of FeOOH/Ni(OH)2 for excellent oxygen evolution reaction via Cr modification". Dalton Transactions 50, nr 28 (2021): 9746–53. http://dx.doi.org/10.1039/d1dt01469b.

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Cr-Doped FeOOH/Ni(OH)₂ electrocatalysts were prepared via a facile hydrothermal method at 120 °C. The electrocatalyst exhibited outstanding OER performance, with an overpotential of 291 mV at 50 mA cm⁻².

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Saha, Sulay, Koshal Kishor i Raj Ganesh S. Pala. "Climbing with support: scaling the volcano relationship through support–electrocatalyst interactions in electrodeposited RuO2 for the oxygen evolution reaction". Catalysis Science & Technology 11, nr 13 (2021): 4342–52. http://dx.doi.org/10.1039/d1cy00375e.

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The interfacial charge transfer and support-induced electrocatalyst faceting in thin catalysts enable ‘climbing up’ the volcano map for OER electrocatalysts. The conductivity of the support determines the OER activity of thick catalysts.

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Banti, Angeliki, Kalliopi Maria Papazisi, Stella Balomenou i Dimitrios Tsiplakides. "Effect of Calcination Temperature on the Activity of Unsupported IrO2 Electrocatalysts for the Oxygen Evolution Reaction in Polymer Electrolyte Membrane Water Electrolyzers". Molecules 28, nr 15 (2.08.2023): 5827. http://dx.doi.org/10.3390/molecules28155827.

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Polymer electrolyte membrane (PEM) water electrolyzers suffer mainly from slow kinetics regarding the oxygen evolution reaction (OER). Noble metal oxides, like IrO2 and RuO2, are generally more active for OER than metal electrodes, exhibiting low anodic overpotentials and high catalytic activity. However, issues like electrocatalyst stability under continuous operation and cost minimization through a reduction in the catalyst loading are of great importance to the research community. In this study, unsupported IrO2 of various particle sizes (different calcination temperatures) were evaluated for the OER and as anode electrodes for PEM water electrolyzers. The electrocatalysts were synthesized by the modified Adams method, and the effect of calcination temperature on the properties of IrO2 electrocatalysts is investigated. Physicochemical characterization was conducted using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area measurement, high-resolution transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses. For the electrochemical performance of synthesized electrocatalysts in the OER, cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were conducted in a typical three-cell electrode configuration, using glassy carbon as the working electrode, which the synthesized electrocatalysts were cast on in a 0.5 M H2SO4 solution. The materials, as anode PEM water electrolysis electrodes, were further evaluated in a typical electrolytic cell using a Nafion®115 membrane as the electrolyte and Pt/C as the cathode electrocatalyst. The IrO2 electrocatalyst calcined at 400 °C shows high crystallinity with a 1.24 nm particle size, a high specific surface area (185 m2 g−1), and a high activity of 177 mA cm−2 at 1.8 V for PEM water electrolysis.

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Zhu, Yan, Haidong Yang, Kai Lan, Kanwal Iqbal, Yang Liu, Ping Ma, Ziming Zhao, Sha Luo, Yutong Luo i Jiantai Ma. "Optimization of iron-doped Ni3S2 nanosheets by disorder engineering for oxygen evolution reaction". Nanoscale 11, nr 5 (2019): 2355–65. http://dx.doi.org/10.1039/c8nr08469f.

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Disorder engineering were applied in Ni₃S₂, disclosing the relationship between disorder degree and catalytic activity for OER process. The optimized electrocatalysts (Fe_7.2%-Ni₃S₂ NSs/NF) with moderate amorphization degrees had been fabricated as a prominent alternative OER electrocatalyst.

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Samo, A. H., U. Aftab, D. X. Cao, M. Ahmed, M. N. Lakhan, V. Kumar, A. Asif i A. Ali. "Schematic synthesis of cobalt-oxide (Co3O4) supported cobalt-sulfide (CoS) composite for oxygen evolution reaction". Digest Journal of Nanomaterials and Biostructures 17, nr 1 (styczeń 2022): 109–20. http://dx.doi.org/10.15251/djnb.2022.171.109.

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Development of electrocatalysts has received great attention for storage and energy conversion technologies. Different electrocatalysts for oxygen evolution reaction (OER) have been produced and investigated but their role is not sufficient to mark of Ruthenium oxide (RuO2). Therefore, it is global requirement to produce an efficient, lower cost and earth-abundant electrocatalyst for OER. Herein, cobalt oxide-cobalt sulfide (Co3O4-CoS2) composite have been synthesized via hydrothermal chemical method with active performance OER. The desired overpotential is 280 mV to achieve current density of 20 mA cm-2 of as prepared composite with Tafel slope value of 74 mV dec-1 . As prepared Co3O4-CoS2 composite has efficient stability of 30 hours for long term electrochemical performance.

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Kim, Hyo-Young, i Young-Wan Ju. "Fabrication of Mn-N-C Catalyst for Oxygen Reduction Reactions Using Mn-Embedded Carbon Nanofiber". Energies 13, nr 10 (18.05.2020): 2561. http://dx.doi.org/10.3390/en13102561.

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The development of efficient and cost-effective electrocatalysts for oxygen reduction reactions (ORR) is one of the most crucial goals in the field of energy conversion devices such as fuel cells or metal-air batteries. Until now, the platinum-based catalyst has been considered the gold standard electrocatalyst and is widely used for ORR. In recent times, transition metal-nitrogen (N)-carbon (C)-based electrocatalysts have verified ORR performances comparable to novel metal-based catalysts. However, due to the complex production methods and low yield, their high price is their one major disadvantage compared to platinum-based catalysts. Herein, we present a transition metal-N-C electrochemical catalyst prepared by simple electrospinning and heat treatment. The metal- and nitrogen-embedded carbon nanofiber represents considerably enhanced activity for oxygen reduction reactions compared to pristine carbon nanofiber.

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Jia, Lisha, Pawel Wagner i Jun Chen. "Electrocatalyst Derived from NiCu–MOF Arrays on Graphene Oxide Modified Carbon Cloth for Water Splitting". Inorganics 10, nr 4 (13.04.2022): 53. http://dx.doi.org/10.3390/inorganics10040053.

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Electrocatalysts are capable of transforming water into hydrogen, oxygen, and therefore into energy, in an environmentally friendly and sustainable manner. However, the limitations in the research of high performance catalysts act as an obstructer in the development of using water as green energy. Here, we report on a delicate method to prepare novel bimetallic metal organic framework derived electrocatalysts (C–NiCu–BDC–GO–CC) using graphene oxide (GO) modified carbon cloth as a 3D flexible and conductive substrate. The resultant electrocatalyst, C–NiCu–BDC–GO–CC, exhibited very low electron transfer resistance, which benefited from its extremely thin 3D sponge-like morphology. Furthermore, it showed excellent oxygen evolution reaction (OER) activity, achieving 10 mA/cm2 at a low overpotential of 390 mV in 1 M KOH electrolyte with a remarkable durability of 10 h.

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He, Shuaijie, Mingjie Wu, Song Li, Zhiyi Jiang, Hanlie Hong, Sylvain G. Cloutier, Huaming Yang, Sasha Omanovic, Shuhui Sun i Gaixia Zhang. "Research Progress on Graphite-Derived Materials for Electrocatalysis in Energy Conversion and Storage". Molecules 27, nr 24 (7.12.2022): 8644. http://dx.doi.org/10.3390/molecules27248644.

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High-performance electrocatalysts are critical to support emerging electrochemical energy storage and conversion technologies. Graphite-derived materials, including fullerenes, carbon nanotubes, and graphene, have been recognized as promising electrocatalysts and electrocatalyst supports for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and carbon dioxide reduction reaction (CO2RR). Effective modification/functionalization of graphite-derived materials can promote higher electrocatalytic activity, stability, and durability. In this review, the mechanisms and evaluation parameters for the above-outlined electrochemical reactions are introduced first. Then, we emphasize the preparation methods for graphite-derived materials and modification strategies. We further highlight the importance of the structural changes of modified graphite-derived materials on electrocatalytic activity and stability. Finally, future directions and perspectives towards new and better graphite-derived materials are presented.

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44

Karuppiah, Chelladurai, Balamurugan Thirumalraj, Srinivasan Alagar, Shakkthivel Piraman, Ying-Jeng Jame Li i Chun-Chen Yang. "Solid-State Ball-Milling of Co3O4 Nano/Microspheres and Carbon Black Endorsed LaMnO3 Perovskite Catalyst for Bifunctional Oxygen Electrocatalysis". Catalysts 11, nr 1 (7.01.2021): 76. http://dx.doi.org/10.3390/catal11010076.

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Developing a highly stable and non-precious, low-cost, bifunctional electrocatalyst is essential for energy storage and energy conversion devices due to the increasing demand from the consumers. Therefore, the fabrication of a bifunctional electrocatalyst is an emerging focus for the promotion and dissemination of energy storage/conversion devices. Spinel and perovskite transition metal oxides have been widely explored as efficient bifunctional electrocatalysts to replace the noble metals in fuel cell and metal-air batteries. In this work, we developed a bifunctional catalyst for oxygen reduction and oxygen evolution reaction (ORR/OER) study using the mechanochemical route coupling of cobalt oxide nano/microspheres and carbon black particles incorporated lanthanum manganite perovskite (LaMnO3@C-Co3O4) composite. It was synthesized through a simple and less-time consuming solid-state ball-milling method. The synthesized LaMnO3@C-Co3O4 composite was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction spectroscopy, and micro-Raman spectroscopy techniques. The electrocatalysis results showed excellent electrochemical activity towards ORR/OER kinetics using LaMnO3@C-Co3O4 catalyst, as compared with Pt/C, bare LaMnO3@C, and LaMnO3@C-RuO2 catalysts. The observed results suggested that the newly developed LaMnO3@C-Co3O4 electrocatalyst can be used as a potential candidate for air-cathodes in fuel cell and metal-air batteries.

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45

Karuppiah, Chelladurai, Balamurugan Thirumalraj, Srinivasan Alagar, Shakkthivel Piraman, Ying-Jeng Jame Li i Chun-Chen Yang. "Solid-State Ball-Milling of Co3O4 Nano/Microspheres and Carbon Black Endorsed LaMnO3 Perovskite Catalyst for Bifunctional Oxygen Electrocatalysis". Catalysts 11, nr 1 (7.01.2021): 76. http://dx.doi.org/10.3390/catal11010076.

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Developing a highly stable and non-precious, low-cost, bifunctional electrocatalyst is essential for energy storage and energy conversion devices due to the increasing demand from the consumers. Therefore, the fabrication of a bifunctional electrocatalyst is an emerging focus for the promotion and dissemination of energy storage/conversion devices. Spinel and perovskite transition metal oxides have been widely explored as efficient bifunctional electrocatalysts to replace the noble metals in fuel cell and metal-air batteries. In this work, we developed a bifunctional catalyst for oxygen reduction and oxygen evolution reaction (ORR/OER) study using the mechanochemical route coupling of cobalt oxide nano/microspheres and carbon black particles incorporated lanthanum manganite perovskite (LaMnO3@C-Co3O4) composite. It was synthesized through a simple and less-time consuming solid-state ball-milling method. The synthesized LaMnO3@C-Co3O4 composite was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction spectroscopy, and micro-Raman spectroscopy techniques. The electrocatalysis results showed excellent electrochemical activity towards ORR/OER kinetics using LaMnO3@C-Co3O4 catalyst, as compared with Pt/C, bare LaMnO3@C, and LaMnO3@C-RuO2 catalysts. The observed results suggested that the newly developed LaMnO3@C-Co3O4 electrocatalyst can be used as a potential candidate for air-cathodes in fuel cell and metal-air batteries.

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Xu, Jun, Chan Chen, Zhifei Han, Yuanyuan Yang, Junsheng Li i Qibo Deng. "Recent Advances in Oxygen Electrocatalysts Based on Perovskite Oxides". Nanomaterials 9, nr 8 (14.08.2019): 1161. http://dx.doi.org/10.3390/nano9081161.

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Electrochemical oxygen reduction and oxygen evolution are two key processes that limit the efficiency of important energy conversion devices such as metal–air battery and electrolysis. Perovskite oxides are receiving discernable attention as potential bifunctional oxygen electrocatalysts to replace precious metals because of their low cost, good activity, and versatility. In this review, we provide a brief summary on the fundamentals of perovskite oxygen electrocatalysts and a detailed discussion on emerging high-performance oxygen electrocatalysts based on perovskite, which include perovskite with a controlled composition, perovskite with high surface area, and perovskite composites. Challenges and outlooks in the further development of perovskite oxygen electrocatalysts are also presented.

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Sung, Yung-Eun, Heejong Shin i Jae Jeong Kim. "(Digital Presentation) Design of Metal/Metal Oxide Nanomaterials for Highly Active, Selective, and Durable Electrocatalysts". ECS Meeting Abstracts MA2022-02, nr 42 (9.10.2022): 1553. http://dx.doi.org/10.1149/ma2022-02421553mtgabs.

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Electrocatalysis is a key part of renewable energy conversion in the future energy system. Sustainable energy conversion and chemical production require catalyst structure with high activity, durability, and product selectivity. In general, nanoscale electrocatalysts suffer various degradation phenomena during electrocatalysis, which leads to critical performance loss. Recently, the various hybrid nanostructures (such as ordered structure, metal/carbon encapsulation, or metal/metal oxide) have been highly investigated to achieve promising catalytic performances and enhanced stabilities. In this presentation, we will cover three different types of nanomaterials as highly active and stable electrocatalysts for oxygen reduction reaction (ORR). First, the alloy nanoparticles with ordered structures exhibit novel catalytic properties from their unique electronic and geometric structures. In particular, Pt alloys with atomically ordered crystal structures have been found to largely improve both electrocatalytic activity and stability for ORR through increased electronic interaction between Pt and other transition metals. Similarly, we recently demonstrated that well-controlled Co-, Mn- and Fe-based ternary or binary oxide nanocatalysts have an exceptionally high ORR activity, in addition to the promising electrocatalytic stability. Therefore, it is very important to synthesize well-ordered alloy nanocrystals to obtain highly durable and active electrocatalysts with respect to their structural and compositional properties. Second, we will show the strategic employment of carbon shells on electrocatalyst surfaces to enhance stability in the electrochemical process. Carbon shells can beneficially shield catalyst surfaces from electrochemical degradation and physical agglomeration. Thus carbon shells can effectively preserve the initial active site structure during electrocatalysis. The carbon shell also provides a confined environment at interfaces, enabling unconventional electrochemical behaviors. Finally, we will suggest an effective strategy to construct metal/oxide interfaces, precisely modulating the metal/oxide interfacial interactions in the nanoscale. By controlling the interface and strain effect on catalytic activity, we can achieve high active and stable metal oxide systems for ORR. We would like to describe the details of the above results, for investigating structure-activity relationships in electrocatalytic processes. Only when we start to comprehend the fundamentals behind electrocatalysis on the structure and interface of metal/metal oxide nanocrystals, they can be further advanced to be sustainable in long-term device operation.

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Bae, Youngjoon, Hyeokjun Park, Youngmin Ko, Hyunah Kim, Sung Kwan Park i Kisuk Kang. "Bifunctional Oxygen Electrocatalysts for Lithium−Oxygen Batteries". Batteries & Supercaps 2, nr 4 (6.02.2019): 311–25. http://dx.doi.org/10.1002/batt.201800127.

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49

Bae, Youngjoon, Hyeokjun Park, Youngmin Ko, Hyunah Kim, Sung Kwan Park i Kisuk Kang. "Bifunctional Oxygen Electrocatalysts for Lithium‐Oxygen Batteries". Batteries & Supercaps 2, nr 4 (kwiecień 2019): 269. http://dx.doi.org/10.1002/batt.201900039.

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Abruna, Hector. "(Invited) Novel Materials and Operando Methods for Alkaline Electrocatalysis". ECS Meeting Abstracts MA2022-02, nr 43 (9.10.2022): 1614. http://dx.doi.org/10.1149/ma2022-02431614mtgabs.

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This presentation will deal with the development of new materials and operando methods for electrocatalysis in alkaline media. The presentation will begin with a brief overview of the methods employed with emphasis on the use of X-ray based methods and transmission electron microscopy (TEM) under active potential control. The utility of these methods will be illustrated with selected examples focusing on non-precious metal oxides and nitrides as electrocatalysts for the oxygen reduction reaction (ORR), and Ni based systems for the HOR. Fuel cell (MEA) testing of integrated systems employing non-precious metal electrocatalysts will also be discussed. The presentation will conclude with an assessment of future directions.

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