Atomic Cu Sites Engineering Enables Efficient CO2 Electroreduction to Methane with High CH4/C2H4 Ratio

Electrochemical reduction of CO 2 into high-value hydrocarbons and alcohols by using Cu-based catalysts is a promising and attractive technology for CO 2 capture and utilization, resulting from their high catalytic activity and selectivity. The mobility and accessibility of active sites in Cu-based catalysts significantly hinder the development of efficient Cu-based catalysts for CO 2 electrochemical reduction reaction (CO 2 RR). Herein, a facile and effective strategy is developed to engineer accessible and structural stable Cu sites by incorporating single atomic Cu into the nitrogen cavities of the host graphitic carbon nitride (g-C 3 N 4 ) as the active sites for CO 2 -to-CH 4 conversion in CO 2 RR. By regulating the coordination and density of Cu sites in g-C 3 N 4 , an optimal catalyst corresponding to a one Cu atom in one nitrogen cavity reaches the highest CH 4 Faraday efficiency of 49.04% and produces the products with a high CH 4 /C 2 H 4 ratio over 9. This work provides the first experimental study on g-C 3 N 4 -supported single Cu atom catalyst for efficient CH 4 production from CO 2 RR and suggests a principle in designing highly stable and selective high-efficiency Cu-based catalysts for CO 2 RR by engineering Cu active sites in 2D materials with porous crystal structures.