Tandem modulation strategy for copper-based catalysts: Towards efficient C-C coupling in the electrochemical reduction of carbon dioxide.

The CO2 reduction reaction (CO2RR) is notable for its multiple advantages, such as mild reaction conditions, controllable product output, and ease of operation. The chemistry of CO2RR to produce multicarbon products involves multiple electron-proton transfer steps, in which the adsorption of CO intermediates is usually the key rate-determining step of the reaction. Currently, Cu is the only metal catalyst known to efficiently reduce CO2 to multicarbon products, mainly due to its appropriate adsorption energy for CO intermediates. However, single Cu catalysts often face challenges such as excessively high overpotentials and poor selectivity, which limit their potential application in CO2 reduction. In recent years, electrochemical CO2 reduction using copper-based tandem catalysts has become an effective strategy to enhance the overall performance of CO2RR and a hot topic in the research field. Here we review recent research advances in the field of electrochemical CO2RR where tandem methods have been applied. The major points are the following: (1) the tandem process allows for more precise control of the electrochemical reduction pathway, thereby increasing the yield of the target product while reducing the generation of by-products; (2) Mass transportation of *CO intermediates and spatial management is important for the generation of multicarbon products; (3) a variety of tandem means for upgrading the product to a deeply reduced product are reviewed.