The electrochemical carbon dioxide (CO₂) reduction reaction (CO₂RR) is among the most promising approaches used to transform greenhouse gas into useful fuels and chemicals. However, the reaction suffers from low selectivity, high overpotential, and low reaction rate. Active site identification in the CO₂RR is vital for the understanding of the reaction mechanism and the rational development of new electrocatalysts with both high selectivity and stability. Herein, in situ characterization monitoring of active sites during the reaction is summarized and a general understanding of active sites on the various catalysts in the CO₂RR, including metal‐based catalysts, carbon‐based catalysts, and metal‐organic frameworks‐based electrocatalysts is updated. For each type of electrocatalysts, the reaction pathway and real active sites are proposed based on in situ characterization techniques and theoretical calculations. Finally, the key limitations and challenges observed for the electrochemical fixation of CO₂ is presented. It is expected that this review will provide new insights and directions into further scientific development and practical applicability of CO₂ electroreduction.

中文翻译：

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电化学 CO2 还原反应活性位点的研究：从原位表征到合理设计

电化学二氧化碳（CO ₂）还原反应（CO ₂ RR）是将温室气体转化为有用燃料和化学品的最有前途的方法之一。然而，该反应存在选择性低、过电位高、反应速率低的问题。CO ₂ RR中活性位点的识别对于理解反应机理和合理开发具有高选择性和稳定性的新型电催化剂至关重要。本文总结了反应过程中活性位点的原位表征监测，并对CO ₂ RR中各种催化剂上的活性位点有了一般性的了解，包括金属基催化剂、碳基催化剂和金属有机骨架基电催化剂已更新。对于每种类型的电催化剂，基于原位表征技术和理论计算提出了反应途径和真实活性位点。最后，提出了电化学固定CO _{2所观察到的主要局限性和挑战。}预计该综述将为CO ₂电还原的进一步科学发展和实际应用提供新的见解和方向。