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Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Recent Progress and New Horizons in Emerging Novel MXene-Based Materials for Energy Storage Applications for Current Environmental Remediation and Energy Crises Karim Khan, Ayesha Khan Tareen, Muhammad Iqbal, Ye Zhang, Asif Mahmood, Nasir mahmood, Zhe Shi, Chunyang Ma, J. R. Rosin, Han Zhang Electrochemical Energy Reviews    2024, 7 (3): 22-.   DOI: 10.1007/s41918-024-00224-x Abstract （595）      PDF       Knowledge map    Save Unsustainable fossil fuel energy usage and its environmental impacts are the most significant scientific challenges in the scientific community. Two-dimensional (2D) materials have received a lot of attention recently because of their great potential for application in addressing some of society’s most enduring issues with renewable energy. Transition metal-based nitrides, carbides, or carbonitrides, known as “MXenes”, are a relatively new and large family of 2D materials. Since the discovery of the first MXene, Ti3C2 in 2011 has become one of the fastest-expanding families of 2D materials with unique physiochemical features. MXene surface terminations with hydroxyl, oxygen, fluorine, etc., are invariably present in the so far reported materials, imparting hydrophilicity to their surfaces. The current finding of multi-transition metal-layered MXenes with controlled surface termination capacity opens the door to fabricating unique structures for producing renewable energy. MXene NMs-based flexible chemistry allows them to be tuned for energy-producing/storage, electromagnetic interference shielding, gas/biosensors, water distillation, nanocomposite reinforcement, lubrication, and photo/electro/chemical catalysis. This review will first discuss the advancement of MXenes synthesis methods, their properties/stability, and renewable energy applications. Secondly, we will highlight the constraints and challenges that impede the scientific community from synthesizing functional MXene with controlled composition and properties. We will further reveal the high-tech implementations for renewable energy storage applications along with future challenges and their solutions. Related Articles | Metrics | Comments（0） Select PGM-Free Biomass-Derived Electrocatalysts for Oxygen Reduction in Energy Conversion Devices: Promising Materials Stefano Zago, Laura C. Scarpetta Pizo, José H. Zagal, Linlin Li, Stefania Specchia Electrochemical Energy Reviews    2024, 7 (1): 1-.   DOI: 10.1007/s41918-023-00197-3 Abstract （340）      PDF       Knowledge map    Save Biomass is a low-cost, abundant and renewable resource that can be used to manufacture porous carbon-based materials for a variety of applications. Different mesoporous carbon supports can be obtained from the various synthetic approaches that are aimed at increasing the specific surface area and functionalization. Currently, most of the biomass is used for energy recovery. The circular economy approach could lead to the development of cheap and sustainable materials, and turning of wastes into a precious resource. In this review, we provide the recent advances in the field of electrochemistry for porous carbon materials derived from biomass, which offers wider applications in proton exchange membrane fuel cells (PEMFCs), anion exchange membrane fuel cells (AEMFCs) and Zn-air batteries (ZABs). The focus is on understanding the required properties of the materials and the role of synthetic pathways in platinum group metal (PGM) free electrocatalysts. The most promising materials are evaluated towards the oxygen reduction reaction (ORR) in PEMFC, AEMFC, and ZAB. The results achieved showed that the expected performances on these energy conversion devices still lack for deployment in practice, especially if compared with commercially available PGM-free electrocatalysts. This review article provides insights on how to improve the actual electrocatalytic activity of biomass-derived materials. Related Articles | Metrics | Comments（0） Select Advanced Electrode Structures for Proton Exchange Membrane Fuel Cells: Current Status and Path Forward Gaoqiang Yang, ChungHyuk Lee, Xiaoxiao Qiao, Siddharth Komini Babu, Ulises Martinez, Jacob S. Spendelow Electrochemical Energy Reviews    2024, 7 (1): 9-.   DOI: 10.1007/s41918-023-00208-3 Abstract （299）      PDF       Knowledge map    Save Proton exchange membrane fuel cells (PEMFCs) have demonstrated their viability as a promising candidate for clean energy applications. However, performance of conventional PEMFC electrodes, especially the cathode electrode, suffers from low catalyst utilization and sluggish mass transport due to the randomly distributed components and tortuous transport pathways. Development of alternative architectures in which the electrode structure is controlled across a range of length scales provides a promising path toward overcoming these limitations. Here, we provide a comprehensive review of recent research and development of advanced electrode structures, organized by decreasing length-scale from the millimeter-scale to the nanometer-scale. Specifically, advanced electrode structures are categorized into five unique architectures for specific functions: (1) macro-patterned electrodes for enhanced macro-scale mass transport, (2) micro-patterned electrodes for enhanced micro-scale mass transport, (3) electrospun electrodes with fiber-based morphology for enhanced in-plane proton transport and through-plane O2 transport, (4) enhanced-porosity electrodes for improved oxygen transport through selective inclusion of void space, and (5) catalyst film electrodes for elimination of carbon corrosion and ionomer poisoning. The PEMFC performance results achieved from each alternative electrode structure are presented and tabulated for comparison with conventional electrode architectures. Moreover, analysis of mechanisms by which new electrode structures can improve performance is presented and discussed. Finally, an overview of current limitations and future research needs is presented to guide the development of electrode structures for next generation PEMFCs. Related Articles | Metrics | Comments（0） Select Emerging Atomically Precise Metal Nanoclusters and Ultrasmall Nanoparticles for Efficient Electrochemical Energy Catalysis: Synthesis Strategies and Surface/Interface Engineering Mingjie Wu, Fang Dong, Yingkui Yang, Xun Cui, Xueqin Liu, Yunhai Zhu, Dongsheng Li, Sasha Omanovic, Shuhui Sun, Gaixia Zhang Electrochemical Energy Reviews    2024, 7 (1): 10-.   DOI: 10.1007/s41918-024-00217-w Abstract （314）      PDF       Knowledge map    Save Atomically precise metal nanocluster and ultrasmall nanoparticle catalysts have garnered significant interest in electrocatalysis applications due to their unique geometric and electronic structures. As an intermediate state between single-atom catalysts (SACs) and nanoparticles in size, nanoclusters with specific low nuclearity provide designated metallic states with multiple atoms or surface sites for the adsorption and transformation of reactants/intermediates. The unique catalytic properties of nanoclusters offer a novel platform for designing effective and efficient electrocatalysts, potentially surpassing the SACs in certain catalytic reactions. This review summarizes and discusses the latest progress of nanoclusters and ultrasmall nanoparticles for various electrocatalysis applications, including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), CO2 reduction reaction (CO2RR), nitrogen reduction reaction (NRR), hydrogen evolution reaction (HER), various chemicals oxidation reaction (COR), etc. Specifically, this review highlights surface/interface chemical modification strategies and structure-properties relationships, drawing from the atomic-level insights to determine electrocatalytic performance. Lastly, we present the challenges and opportunities associated with nanocluster or ultrasmall nanoparticle electrocatalysts. Related Articles | Metrics | Comments（0） Select Application of Solid Catalysts with an Ionic Liquid Layer (SCILL) in PEMFCs: From Half-Cell to Full-Cell Xiaojing Cheng, Guanghua Wei, Liuxuan Luo, Jiewei Yin, Shuiyun Shen, Junliang Zhang Electrochemical Energy Reviews    2023, 6 (4): 33-.   DOI: 10.1007/s41918-023-00195-5 Abstract （398）      PDF       Knowledge map    Save The advantages of zero emission and high energy efficiency make proton exchange membrane fuel cells (PEMFCs) promising options for future energy conversion devices. To address the cost issue associated with Pt-based electrocatalysts, considerable effort over the past several years has been devoted to catalyst surface modification by means of novel electrocatalysts, such as solid catalysts with an ionic liquid layer (SCILL), which improves both the oxygen reduction reaction (ORR) activity and durability. However, despite numerous reports of dramatically enhanced ORR activity, as determined via the rotating disk electrode (RDE) method, few studies on the application of SCILLs in membrane electrode assembly (MEA) have been reported. The underlying reason lies in the well-acknowledged technological gap between half-cells and full-cells, which originates from the disparate microenvironments for three phase boundaries. Therefore, the objective of this review is to compare the detailed information about improvements in fuel cell performance in both half- and full-cells, thus increasing the fundamental understanding of the mechanism of SCILL. In this review, the concept of SCILL and its origin are introduced, the outstanding electrochemical performance of SCILL catalysts in both RDE and MEA measurements is summarized, and the durability of SCILL catalysts is analysed. Subsequently, proposed mechanisms for the enhanced ORR activity in half-cells, the improved oxygen transport in full-cells and the boosted stability of SCILL catalysts are discussed, while the effects of the IL chemical structure, IL loading as well as the operating conditions on the performance and lifetime of SCILL catalysts are assessed. Finally, comprehensive conclusions are presented, and perspectives are proposed in the last section. It is believed that the new insight presented in this review could provide guidance for the further development of SCILLs in low-Pt PEMFCs. Related Articles | Metrics | Comments（0） Select Recent Advances on PEM Fuel Cells: From Key Materials to Membrane Electrode Assembly Shanyun Mo, Lei Du, Zhiyin Huang, Junda Chen, Yangdong Zhou, Puwei Wu, Ling Meng, Ning Wang, Lixin Xing, Mingquan Zhao, Yunsong Yang, Junke Tang, Yuquan Zou, Siyu Ye Electrochemical Energy Reviews    2023, 6 (3): 28-.   DOI: 10.1007/s41918-023-00190-w Abstract （460）      PDF       Knowledge map    Save In recent years, proton exchange membrane (PEM) fuel cells have regained worldwide attention from academia, industries, investors, and governments. The prospect of PEM fuel cells has turned into reality, with fuel cell vehicles successfully launched in the market. However, today’s fuel cells remain less competitive than combustion engines and batteries, primarily due to their high cost and short lifetime, which are significantly affected by the membrane electrode assembly (MEA), or the “chips” of PEM fuel cells. Therefore, many efforts have been devoted to developing advanced materials and manufacturing processes for MEAs. In this paper, we critically review the recent progress of key materials for MEAs, focusing on how to integrate materials into electrodes and MEAs. We also present the most advanced designs and manufacturing techniques of MEAs and discuss their possible constraints. Finally, perspectives on future R&D directions of materials and MEAs are provided. This review aims to bridge the gaps between academic material research and industrial manufacturing process development. Related Articles | Metrics | Comments（0） Select Direct Alcohol Fuel Cells: A Comparative Review of Acidic and Alkaline Systems Enrico Berretti, Luigi Osmieri, Vincenzo Baglio, Hamish A. Miller, Jonathan Filippi, Francesco Vizza, Monica Santamaria, Stefania Specchia, Carlo Santoro, Alessandro Lavacchi Electrochemical Energy Reviews    2023, 6 (3): 30-.   DOI: 10.1007/s41918-023-00189-3 Abstract （402）      PDF       Knowledge map    Save In the last 20 years, direct alcohol fuel cells (DAFCs) have been the subject of tremendous research efforts for the potential application as on-demand power sources. Two leading technologies respectively based on proton exchange membranes (PEMs) and anion exchange membranes (AEMs) have emerged: the first one operating in an acidic environment and conducting protons; the second one operating in alkaline electrolytes and conducting hydroxyl ions. In this review, we present an analysis of the state-of-the-art acidic and alkaline DAFCs fed with methanol and ethanol with the purpose to support a comparative analysis of acidic and alkaline systems, which is missing in the current literature. A special focus is placed on the effect of the reaction stoichiometry in acidic and alkaline systems. Particularly, we point out that, in alkaline systems, OH- participates stoichiometrically to reactions, and that alcohol oxidation products are anions. This aspect must be considered when designing the fuel and when making an energy evaluation from a whole system perspective. Related Articles | Metrics | Comments（0） Select Structure, Property, and Performance of Catalyst Layers in Proton Exchange Membrane Fuel Cells Jian Zhao, Huiyuan Liu, Xianguo Li Electrochemical Energy Reviews    2023, 6 (2): 13-.   DOI: 10.1007/s41918-022-00175-1 Abstract （955）      PDF       Knowledge map    Save Catalyst layer (CL) is the core component of proton exchange membrane (PEM) fuel cells, which determines the performance, durability, and cost. However, difficulties remain for a thorough understanding of the CLs’ inhomogeneous structure, and its impact on the physicochemical and electrochemical properties, operating performance, and durability. The inhomogeneous structure of the CLs is formed during the manufacturing process, which is sensitive to the associated materials, composition, fabrication methods, procedures, and conditions. The state-of-the-art visualization and characterization techniques are crucial to examine the CL structure. The structure-dependent physicochemical and electrochemical properties are then thoroughly scrutinized in terms of fundamental concepts, theories, and recent progress in advanced experimental techniques. The relation between the CL structure and the associated effective properties is also examined based on experimental and theoretical findings. Recent studies indicated that the CL inhomogeneous structure also strongly affects the performance and degradation of the whole fuel cell, and thus, the interconnection between the fuel cell performance, failure modes, and CL structure is comprehensively reviewed. An analytical model is established to understand the effect of the CL structure on the effective properties, performance, and durability of the PEM fuel cells. Finally, the challenges and prospects of the CL structure-associated studies are highlighted for the development of high-performing PEM fuel cells. Related Articles | Metrics | Comments（0） Select Overcoming the Electrode Challenges of High-Temperature Proton Exchange Membrane Fuel Cells Quentin Meyer, Chujie Yang, Yi Cheng, Chuan Zhao Electrochemical Energy Reviews    2023, 6 (2): 16-.   DOI: 10.1007/s41918-023-00180-y Abstract （980）      PDF       Knowledge map    Save Proton exchange membrane fuel cells (PEMFCs) are becoming a major part of a greener and more sustainable future. However, the costs of high-purity hydrogen and noble metal catalysts alongside the complexity of the PEMFC system severely hamper their commercialization. Operating PEMFCs at high temperatures (HT-PEMFCs, above 120 °C) brings several advantages, such as increased tolerance to contaminants, more affordable catalysts, and operations without liquid water, hence considerably simplifying the system. While recent progresses in proton exchange membranes for HT-PEMFCs have made this technology more viable, the HT-PEMFC viscous acid electrolyte lowers the active site utilization by unevenly diffusing into the catalyst layer while it acutely poisons the catalytic sites. In recent years, the synthesis of platinum group metal (PGM) and PGM-free catalysts with higher acid tolerance and phosphate-promoted oxygen reduction reaction, in conjunction with the design of catalyst layers with improved acid distribution and more triple-phase boundaries, has provided great opportunities for more efficient HT-PEMFCs. The progress in these two interconnected fields is reviewed here, with recommendations for the most promising routes worthy of further investigation. Using these approaches, the performance and durability of HT-PEMFCs will be significantly improved. Related Articles | Metrics | Comments（0） Select Pt-Based Intermetallic Compound Catalysts for the Oxygen Reduction Reaction: Structural Control at the Atomic Scale to Achieve a Win–Win Situation Between Catalytic Activity and Stability Jue Wang, Fengwen Pan, Wenmiao Chen, Bing Li, Daijun Yang, Pingwen Ming, Xuezhe Wei, Cunman Zhang Electrochemical Energy Reviews    2023, 6 (1): 6-.   DOI: 10.1007/s41918-022-00141-x Abstract （1705）      PDF       Knowledge map    Save The development of ordered Pt-based intermetallic compounds is an effective way to optimize the electronic characteristics of Pt and its disordered alloys, inhibit the loss of transition metal elements, and prepare fuel cell catalysts with high activity and long-term durability for the oxygen reduction reaction (ORR). This paper reviews the structure–activity characteristics, research advances, problems, and improvements in Pt-based intermetallic compound fuel cell catalysts for the ORR. First, the structural characteristics and performance advantages of Pt-based intermetallic compounds are analyzed and explained. Second, starting with 3d transition metals such as Fe, Co, and Ni, whose research achievements are common, the preparation process and properties of Pt-based intermetallic compound catalysts for the ORR are introduced in detail according to element types. Third, in view of preparation problems, improvements in the preparation processes of Pt-based intermetallic compounds are also summarized in regard to four aspects: coating to control the crystal size, doping to promote ordering transformation, constructing a “Pt skin” to improve performance, and anchoring and confinement to enhance the interaction between the crystal and support. Finally, by analyzing the research status of Pt-based intermetallic compound catalysts for the ORR, prospective research directions are suggested. Related Articles | Metrics | Comments（0） Select A Review of Solid Electrolyte Interphase (SEI) and Dendrite Formation in Lithium Batteries Borong Li, Yu Chao, Mengchao Li, Yuanbin Xiao, Rui Li, Kang Yang, Xiancai Cui, Gui Xu, Lingyun Li, Chengkai Yang, Yan Yu, David P. Wilkinson, Jiujun Zhang Electrochemical Energy Reviews    2023, 6 (1): 7-.   DOI: 10.1007/s41918-022-00147-5 Abstract （1951）      PDF       Knowledge map    Save Lithium-metal batteries with high energy/power densities have significant applications in electronics, electric vehicles, and stationary power plants. However, the unstable lithium-metal-anode/electrolyte interface has induced insufficient cycle life and safety issues. To improve the cycle life and safety, understanding the formation of the solid electrolyte interphase (SEI) and growth of lithium dendrites near the anode/electrolyte interface, regulating the electrodeposition/electrostripping processes of Li+, and developing multiple approaches for protecting the lithium-metal surface and SEI layer are crucial and necessary. This paper comprehensively reviews the research progress in SEI and lithium dendrite growth in terms of their classical electrochemical lithium plating/stripping processes, interface interaction/nucleation processes, anode geometric evolution, fundamental electrolyte reduction mechanisms, and effects on battery performance. Some important aspects, such as charge transfer, the local current distribution, solvation, desolvation, ion diffusion through the interface, inhibition of dendrites by the SEI, additives, models for dendrite formation, heterogeneous nucleation, asymmetric processes during stripping/plating, the host matrix, and in situ nucleation characterization, are also analyzed based on experimental observations and theoretical calculations. Several technical challenges in improving SEI properties and reducing lithium dendrite growth are analyzed. Furthermore, possible future research directions for overcoming the challenges are also proposed to facilitate further research and development toward practical applications. Related Articles | Metrics | Comments（0） Select Recent Progress in High Entropy Alloys for Electrocatalysts Kun Wang, Jianhao Huang, Haixin Chen, Yi Wang, Wei Yan, Xianxia Yuan, Shuqin Song, Jiujun Zhang, Xueliang Sun Electrochemical Energy Reviews    2022, 5 (S1): 17-.   DOI: 10.1007/s41918-022-00144-8 Abstract （599）      PDF       Knowledge map    Save High entropy alloys (HEAs), which can incorporate five or more constituents into a single phase stably, have received considerable attention in recent years. The composition/structure complexity and adjustability endow them with a huge design space to adjust electronic structure, geometric configuration as well as catalytic activity through constructing reaction active sites with optimal binding energies of different reaction intermediates. This paper reviews the recent progress on the preparation methods, characterization techniques, electrocatalytic applications and functional mechanisms of HEAs-based electrocatalysts for hydrogen evolution, oxygen evolution and oxygen reduction reactions. The synthesis approaches for HEAs from bottom-up (high-energy ball milling, cryo-milling, melt-spinning and dealloying) to top-down strategies (carbothermal shock, sputtering deposition and solvothermal) and the corresponding materials characterizations are discussed and analyzed. By summarizing and analyzing the electrocatalytic performance of HEAs for diverse electrocatalytic reactions in water electrolysis cells, metal-air batteries and fuel cells, the basic principle of their designs and the relevant mechanisms are discussed. The technical challenges and prospects of HEAs-based electrocatalysts are also summarized with the proposed further research directions. This review can provide a beneficial theoretical reserve and experimental guidance for developing high performance electrocatalytic materials via the paradigm of high entropy. Related Articles | Metrics | Comments（0） Select Solid-State Electrochemistry and Solid Oxide Fuel Cells: Status and Future Prospects San Ping Jiang Electrochemical Energy Reviews    2022, 5 (S1): 21-.   DOI: 10.1007/s41918-022-00160-8 Abstract （694）      PDF       Knowledge map    Save Solid-state electrochemistry (SSE) is an interdisciplinary field bridging electrochemistry and solid-state ionics and deals primarily with the properties of solids that conduct ions in the case of ionic conducting solid electrolytes and electrons and/or electron holes in the case of mixed ionic and electronic conducting materials. However, in solid-state devices such as solid oxide fuel cells (SOFCs), there are unique electrochemical features due to the high operating temperature (600-1 000℃) and solid electrolytes and electrodes. The solid-to-solid contact at the electrode/electrolyte interface is one of the most distinguished features of SOFCs and is one of the fundamental reasons for the occurrence of most importance phenomena such as shift of the equipotential lines, the constriction effect, polarization-induced interface formation, etc. in SOFCs. The restriction in placing the reference electrode in solid electrolyte cells further complicates the SSE in SOFCs. In addition, the migration species at the solid electrode/electrolyte interface is oxygen ions, while in the case of the liquid electrolyte system, the migration species is electrons. The increased knowledge and understanding of SSE phenomena have guided the development of SOFC technologies in the last 30-40 years, but thus far, no up-to-date reviews on this important topic have appeared. The purpose of the current article is to review and update the progress and achievements in the SSE in SOFCs, largely based on the author's past few decades of research and understanding in the feld, and to serve as an introduction to the basics of the SSE in solid electrolyte devices such as SOFCs. Related Articles | Metrics | Comments（0） Select Fuel Cell Reactors for the Clean Cogeneration of Electrical Energy and Value-Added Chemicals Fengzhan Si, Subiao Liu, Yue Liang, Xian-Zhu Fu, Jiujun Zhang, Jing-Li Luo Electrochemical Energy Reviews    2022, 5 (S2): 25-.   DOI: 10.1007/s41918-022-00168-0 Abstract （644）      PDF       Knowledge map    Save Fuel cell reactors can be tailored to simultaneously cogenerate value-added chemicals and electrical energy while releasing negligible CO2 emissions or other pollution; moreover, some of these reactors can even "breathe in" poisonous gas as feedstock. Such clean cogeneration favorably offsets the fast depletion of fossil fuel resources and eases growing environmental concerns. These unique reactors inherit advantages from fuel cells:a high energy conversion efficiency and high selectivity. Compared with similar energy conversion devices with sandwich structures, fuel cell reactors have successfully "hit three birds with one stone" by generating power, producing chemicals, and maintaining eco-friendliness. In this review, we provide a systematic summary on the state of the art regarding fuel cell reactors and key components, as well as the typical cogeneration reactions accomplished in these reactors. Most strategies fall short in reaching a win-win situation that meets production demand while concurrently addressing environmental issues. The use of fuel cells (FCs) as reactors to simultaneously produce value-added chemicals and electrical power without environmental pollution has emerged as a promising direction. The FC reactor has been well recognized due to its "one stone hitting three birds" merit, namely, efficient chemical production, electrical power generation, and environmental friendliness. Fuel cell reactors for cogeneration provide multidisciplinary perspectives on clean chemical production, effective energy utilization, and even pollutant treatment, with far-reaching implications for the wider scientific community and society. The scope of this review focuses on unique reactors that can convert low-value reactants and/or industrial wastes to value-added chemicals while simultaneously cogenerating electrical power in an environmentally friendly manner. Related Articles | Metrics | Comments（0） Select Controlled Synthesis of Carbon-Supported Pt-Based Electrocatalysts for Proton Exchange Membrane Fuel Cells Huiyuan Liu, Jian Zhao, Xianguo Li Electrochemical Energy Reviews    2022, 5 (4): 13-.   DOI: 10.1007/s41918-022-00173-3 Abstract （2090）      PDF       Knowledge map    Save Proton exchange membrane fuel cells are playing an increasing role in postpandemic economic recovery and climate action plans. However, their performance, cost, and durability are significantly related to Pt-based electrocatalysts, hampering their large-scale commercial application. Hence, considerable efforts have been devoted to improving the activity and durability of Pt-based electrocatalysts by controlled synthesis in recent years as an effective method for decreasing Pt use, and consequently, the cost. Therefore, this review article focuses on the synthesis processes of carbon-supported Pt-based electrocatalysts, which significantly affect the nanoparticle size, shape, and dispersion on supports and thus the activity and durability of the prepared electrocatalysts. The reviewed processes include (i) the functionalization of a commercial carbon support for enhanced catalyst–support interaction and additional catalytic effects, (ii) the methods for loading Pt-based electrocatalysts onto a carbon support that impact the manufacturing costs of electrocatalysts, (iii) the preparation of spherical and nonspherical Pt-based electrocatalysts (polyhedrons, nanocages, nanoframes, one- and two-dimensional nanostructures), and (iv) the postsynthesis treatments of supported electrocatalysts. The influences of the supports, key experimental parameters, and postsynthesis treatments on Pt-based electrocatalysts are scrutinized in detail. Future research directions are outlined, including (i) the full exploitation of the potential functionalization of commercial carbon supports, (ii) scaled-up one-pot synthesis of carbon-supported Pt-based electrocatalysts, and (iii) simplification of postsynthesis treatments. One-pot synthesis in aqueous instead of organic reaction systems and the minimal use of organic ligands are preferred to simplify the synthesis and postsynthesis treatment processes and to promote the mass production of commercial carbon-supported Pt-based electrocatalysts. Related Articles | Metrics | Comments（0） Select Electrocatalytic Oxygen Reduction to Produce Hydrogen Peroxide: Rational Design from Single-Atom Catalysts to Devices Yueyu Tong, Liqun Wang, Feng Hou, Shi Xue Dou, Ji Liang Electrochemical Energy Reviews    2022, 5 (3): 7-.   DOI: 10.1007/s41918-022-00163-5 Abstract （1927）      PDF       Knowledge map    Save Electrocatalytic production of hydrogen peroxide (H2O2) via the 2e- transfer route of the oxygen reduction reaction (ORR) offers a promising alternative to the energy-intensive anthraquinone process, which dominates current industrial-scale production of H2O2. The availability of cost-effective electrocatalysts exhibiting high activity, selectivity, and stability is imperative for the practical deployment of this process. Single-atom catalysts (SACs) featuring the characteristics of both homogeneous and heterogeneous catalysts are particularly well suited for H2O2 synthesis and thus, have been intensively investigated in the last few years. Herein, we present an in-depth review of the current trends for designing SACs for H2O2 production via the 2e- ORR route. We start from the electronic and geometric structures of SACs. Then, strategies for regulating these isolated metal sites and their coordination environments are presented in detail, since these fundamentally determine electrocatalytic performance. Subsequently, correlations between electronic structures and electrocatalytic performance of the materials are discussed. Furthermore, the factors that potentially impact the performance of SACs in H2O2 production are summarized. Finally, the challenges and opportunities for rational design of more targeted H2O2-producing SACs are highlighted. We hope this review will present the latest developments in this area and shed light on the design of advanced materials for electrochemical energy conversion. Related Articles | Metrics | Comments（0） Select Perovskite Cathode Materials for Low-Temperature Solid Oxide Fuel Cells: Fundamentals to Optimization Zhiheng Li, Mengran Li, Zhonghua Zhu Electrochemical Energy Reviews    2022, 5 (2): 263-311.   DOI: 10.1007/s41918-021-00098-3 Abstract （3325）      PDF       Knowledge map    Save Acceleration of the oxygen reduction reaction at the cathode is paramount in the development of low-temperature solid oxide fuel cells. At low operating temperatures between 450 and 600℃, the interactions between the surface and the bulk of the cathode materials greatly impact the electrode kinetics and consequently determine the overall efficacy and long-term stability of the fuel cells. This review will provide an overview of the recent progress in the understanding of surface-bulk interactions in perovskite oxides as well as their impact on cathode reactivity and stability. This review will also summarize current strategies in the development of cathode materials through bulk doping and surface functionalization. In addition, this review will highlight the roles of surface segregation in the mediation of surface and bulk interactions, which have profound impacts on the properties of cathode surfaces and the bulk and therefore overall cathode performance. Although trade-offs between reactivity and stability commonly exist in terms of catalyst design, opportunities also exist in attaining optimal cathode performance through the modulation of both cathode surfaces and bulk using combined strategies. This review will conclude with future research directions involving investigations into the role of oxygen vacancy and mobility in catalysis, the rational modulation of surface-bulk interactions and the use of advanced fabrication techniques, all of which can lead to optimized cathode performance. Related Articles | Metrics | Comments（0） Select Toward alkaline-stable anion exchange membranes in fuel cells: cycloaliphatic quaternary ammonium-based anion conductors Jiandang Xue, Junfeng Zhang, Xin Liu, Tong Huang, Haifei Jiang, Yan Yin, Yanzhou Qin, Michael D. Guiver Electrochemical Energy Reviews    2022, 5 (2): 348-400.   DOI: 10.1007/s41918-021-00105-7 Abstract （3399）      PDF       Knowledge map    Save Anion exchange membrane (AEM) stability has been a long-standing challenge that limited the widespread development and adoption of AEM fuel cells (AEMFCs). The past five years have been a period of exceptional progress in the development of several alkaline-stable AEMs with remarkable both ex situ and in situ AEMFC stability. Certain cycloaliphatic quaternary ammonium (cQA) (mainly five- and six-membered) based AEMs appear to be among those having the most promising overall performance. In this review, we categorize cQAs as cage-like (such as quaternized 1,4-diazabicyclo[2.2.2]octane, (QDABCO) and quinuclidinium), non-cage-like (such as pyrrolidinium and piperidinium) and N-spirocyclic (such as 6-azonia-spiro[5.5]undecane (ASU)). The degradation mechanisms of categorized cQAs are first elucidated. Through an understanding of how the cations are attacked by strongly nucleophilic OH-, improved structural design of incorporating alkaline-stable cations into AEMs is facilitated. Before a detailed description and comparison of the alkaline stability of cQAs and their respective AEMs, current protocols for the assessment of alkaline stability are discussed in detail. Furthermore, the initial AEMFC performance and fuel cell performance stability based on cQA AEMs are also examined. The main focus and highlight of this review are recent advances (2015-2020) of cQA-based AEMs, which exhibit both excellent cation and membrane alkaline stability. We aim to shed light on the development of alkaline-stable cQA-type AEMs, which are trending in the AEM community, and to provide insights into possible solutions for designing long-lived AEM materials. Related Articles | Metrics | Comments（0） Select Fundamentals, On-Going Advances and Challenges of Electrochemical Carbon Dioxide Reduction Zongkui Kou, Xin Li, Tingting Wang, Yuanyuan Ma, Wenjie Zang, Guangdi Nie, John Wang Electrochemical Energy Reviews    2022, 5 (1): 82-111.   DOI: 10.1007/s41918-021-00096-5 Abstract （2525）      PDF       Knowledge map    Save CO2 reduction|Electrocatalysis|Catalyst design|Mechanism understanding|Fundamental science Related Articles | Metrics | Comments（0） Select High-Temperature Electrochemical Devices Based on Dense Ceramic Membranes for CO2 Conversion and Utilization Wenping Li, Jing-Li Luo Electrochemical Energy Reviews    2021, 4 (3): 518-544.   DOI: 10.1007/s41918-021-00099-2 Abstract （698）      PDF       Knowledge map    Save The adverse effects of global warming and climate change have driven the exploration of feasible routes for CO2 capture, storage, conversion and utilization. The processes related to CO2 conversion in high-temperature electrochemical devices (HTEDs) using dense ceramic membranes are particularly appealing due to the simultaneous realization of highly efficient CO2 conversion and value-added chemical production as well as the generation of electricity and storage of renewable energy in some cases. Currently, most studies are focused on the two processes, CO2 electrolysis and H2O/CO2 co-electrolysis in oxygen-conducting solid oxide electrolysis cell (O-SOEC) reactors. Less attention has been paid to other meaningful CO2-conversion-related processes in HTEDs and systematic summary and analysis are currently not available. This review will fill the gap and classify the CO2-conversion-related processes in HTEDs reported in recent years into four types according to the related reactions, including assisted CO2 reduction to CO, H2O and CO2 co-conversion, dry reforming of methane and CO2 hydrogenation. Firstly, an overview of the fundamentals of HTED processes is presented, and then the related mechanism and research progress of each type of reactions in different HTEDs are elucidated and concluded accordingly. The remaining major technical issues are also briefly introduced. Lastly, the main challenges and feasible solutions as well as the future prospects of HTEDs for CO2-conversion-related processes are also discussed in this review. Related Articles | Metrics | Comments（0）

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