Electrochemical CO2-to-CO conversion: A comprehensive review of recent developments and emerging trends

Electrochemical carbon dioxide reduction (ECO2R) is a well-established method for converting waste CO2 gas into valuable products. Carbon monoxide (CO) is widely studied for its advantages in the electrochemical catalytic reduction of CO2, which is of great importance to the chemical industry. As research on the conversion of electrocatalytic reduction of CO2 to CO has become more widespread, scholars have focused on basic research for industrialization. This paper summarizes the catalysts, electrolytes, and electrolyzers including membranes involved in the reaction process of electrocatalytic reduction of CO2 to CO, with an emphasis on intrinsic mechanism and conversion selection properties such as Faradaic efficiency, current density, and overpotential. Catalysts are classified into two main research categories: carbon-based and non-carbon-based, encompassing various aspects such as size, morphology, grain boundary density tuning, surface modification, and metal-support interaction. Additionally, the abundance of copper metal combined with other metals as catalysts, and single-atom catalysts composed of transition metals are highlighted for their significantly different catalytic behaviors and recent key advancements. For industrial-scale production, we present the types of electrolytes suitable for large-scale CO manufacturing and the structure of the electrolyzer. Finally, we provide a brief review of the future direction of CO2 electrolysis for real-world CO production, focusing on catalyst optimization, technological breakthroughs, electrolyzer design as well as working conditions, membrane innovations, and energy utilization.