Efficient strategies for promoting the electrochemical reduction of CO2 to C2+ products over Cu-based catalysts

Cu-based catalysts have been widely studied for the electrochemical CO2 reduction reaction (CO2RR) to yield high-value-added products with two or more carbons (C2+ products). The rational design of Cu-based catalysts is critical to improve the selectivity and energy efficiency of the CO2RR-to-C2+ process. Herein, we review recent advances in Cu-based catalysts with surface modification for four crucial factors in CO2RR-to-C2+ based on briefly analyzing the reaction mechanisms: (1) surface hydrophobization to inhibit the hydrogen evolution reaction;(2) introduction of CO2-capture materials, halide-ion doping, and Cuδ+/Cu0 synergy to promote CO2 adsorption and activation (3) bifunctional catalysts and locally enhanced electric-thermal fields for modulating CO generation and adsorption; and (4) development of confinement structures and heterostructures, addition of oxidation states or defects, and use of single-atoms with different coordination environments to promote carbon–carbon coupling. In particular, the relationships between the surface properties of Cu-based catalysts and improved activity and C2+ selectivity in CO2RR are discussed, along with strategies for enhancing the stability of the catalyst. Furthermore, the current challenges and potential strategies for future CO2RR-to-C2+ research are discussed in this review.