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

Abstract

Electrochemical reduction of CO₂ into high-value hydrocarbons and alcohols by using Cu-based catalysts is a promising and attractive technology for CO₂ 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 CO₂ electrochemical reduction reaction (CO₂RR). 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-C₃N₄) as the active sites for CO₂-to-CH₄ conversion in CO₂RR. By regulating the coordination and density of Cu sites in g-C₃N₄, an optimal catalyst corresponding to a one Cu atom in one nitrogen cavity reaches the highest CH₄ Faraday efficiency of 49.04% and produces the products with a high CH₄/C₂H₄ ratio over 9. This work provides the first experimental study on g-C₃N₄-supported single Cu atom catalyst for efficient CH₄ production from CO₂RR and suggests a principle in designing highly stable and selective high-efficiency Cu-based catalysts for CO₂RR by engineering Cu active sites in 2D materials with porous crystal structures.