Electrocatalysts with single metal atoms as active sites have received increasing attention owing to their high atomic utilization efficiency and exotic catalytic activity and selectivity. This review aims to provide a comprehensive summary on the recent development of such single-atom electrocatalysts (SAECs) for various energy-conversion reactions. The discussion starts with an introduction of the different types of SAECs, followed by an overview of the synthetic methodologies to control the atomic dispersion of metal sites and atomically resolved characterization using state-of-the-art microscopic and spectroscopic techniques. In recognition of the extensive applications of SAECs, the electrocatalytic studies are dissected in terms of various important electrochemical reactions, including hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR), and nitrogen reduction reaction (NRR). Examples of SAECs are deliberated in each case in terms of their catalytic performance, structure–property relationships, and catalytic enhancement mechanisms. A perspective is provided at the end of each section about remaining challenges and opportunities for the development of SAECs for the targeted reaction.

中文翻译：

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具有单金属原子活性位点的高级电催化剂

具有单个金属原子作为活性位的电催化剂由于其高的原子利用率和奇特的催化活性和选择性而受到越来越多的关注。这篇综述旨在提供有关用于各种能量转化反应的此类单原子电催化剂（SAEC）近期发展的全面概述。讨论首先介绍了不同类型的SAEC，然后概述了使用最新的显微和光谱技术控制金属位点原子分散的合成方法以及原子分辨的表征。认识到SAEC的广泛应用，从各种重要的电化学反应（包括放氢反应（HER），氧释放反应（OER），氧还原反应（ORR），二氧化碳还原反应（CO2RR）和氮还原反应（NRR）。在每种情况下，都以SAEC的催化性能，结构-性质关系和催化增强机制为例来研究SAEC。在每个部分的末尾提供了有关针对目标反应开发SAEC的剩余挑战和机遇的观点。