Research progress on electrochemical CO2 reduction for Cu-based single-atom catalysts

Electrochemical CO2 reduction reaction (CO2 RR) is a critical route to reduce the concentration of CO2 in the atmosphere and solve the energy crisis by converting CO2 into high-value chemicals and fuels. It is therefore crucial to rationally design efficient and cost-effective electrochemical catalysts. Copper (Cu) is found to be an excellent metal catalyst that can reduce CO2 to hydrocarbons and alcohols, especially C2+ products. However, there exist some problems (such as high overpotential and poor selectivity in CO2 RR) that limit the application of Cu-based catalysts. In recent years, single-atom catalysts (SACs) have become an emerging research frontier in the field of heterogeneous catalysis due to their potential high activity, selectivity, and stability. Herein, the recent progress of various Cu-based SACs for CO2 RR has been reviewed, especially on the regulatory strategies for the interaction of the active site with key reaction intermediates. This interaction is important for designing the active site to optimize the multi-electron reduction step and improve the catalytic performance. Meanwhile, different design strategies, including the regulation of metal centers, Cu-based single-atom alloy catalysts (SAAs), non-metal SACs, tandem catalysts, and composite catalysts, have also been discussed. Finally, the current research challenges and future developments of SACs in CO2 RR have been summarized.