Abstract: Electrochemical CO₂ reduction reaction (CO₂RR) has attracted considerable attention in the recent decade for its critical role in the storage of renewable energy and fulfilling of the carbon cycle, and catalysts with varying morphology and modification strategies have been studied to improve the CO₂RR activity and selectivity. However, most of the achievements are focused on preliminary reduction products such as CO and HCOOH. Development and research on electrochemical CO reduction reaction (CORR) are considered to be more promising to achieve multicarbon products and a better platform to understand the mechanism of C-C formation. In this review, we introduce the current achievements of CO₂RR and emphasize the potential of CORR. We provide a summary of how electrolysis environment, electrode substrates, and cell design affect the performance of CORR catalysts in order to offer a guideline of standard operating conditions for CORR research. The composition-structure-activity relationships for CORR catalysts studied in H-cells and gas-phase flow cells are separately analyzed to give a comprehensive understanding of the development of catalyst design. Finally, the reaction mechanism, latest progress, major challenges and potential opportunities of CORR are also analyzed to provide a critical overview for further performance improvement of CORR.This work reviews the recent progress and potential of carbon monoxide reduction (CORR) research. A comprehensive summary of how electrolysis environment, electrode substrate, and cell design affect the performance of CORR catalysts is performed and the composition-structure-activity relationships for CORR catalysts are analyzed.

Key words: Electrolysis, CO reduction, Flow cell design, Copper catalysts