Regulation of intermediate microenvironment for efficient C–C coupling in electrochemical CO2 reduction

The electrochemical carbon dioxide reduction reaction (CO2RR) converts the greenhouse gas CO2 into valuable chemicals under mild conditions and is considered a promising approach to reaching carbon neutralization. However, its efficiency and selectivity towards desired products remain far below the requirements for industrial implementation because of its complex reaction mechanism and diverse intermediates. Particularly, the C–C coupling step in the CO2RR is the key step to ensure a high yield of value-added multi-carbon products. Herein, we discuss a recently developed approach to facilitate the C–C coupling step via the rational tuning of the local microenvironment around active sites. First, recent progress and the mechanism of the CO2RR are briefly described. Next, representative approaches of catalyst engineering, including tandem catalysis, molecular modification, micro-structure regulation, proton donation, hydrophobicity and electric field effect, are highlighted to enrich or regulate the intermediates. Finally, persistent technological challenges are summarized and several personal perspectives are provided to propel the industrial application of the CO2RR.