Non-noble metal single atom-based catalysts for electrochemical reduction of CO2: Synthesis approaches and performance evaluation

Limiting global carbon dioxide (CO₂) emission is imperative to alleviate global warming and meet the growing energy demand. Electrocatalytic CO₂ reduction is a promising approach for achieving this goal. The utilization of single atom-based catalysts (SACs) has garnered substantial attention in this particular field. Although noble metal SACs offer many advantages in CO₂ reduction, their high cost and scarcity have deterred many researchers. Consequently, the focus has shifted toward low-priced transition metals, which have shown better performance than some rare metals. This comprehensive review focuses on the research advances in electrocatalysis for CO₂ reduction reaction using SACs in the past five years. The main synthesis strategies of SACs in recent years are also summarized in detail. Furthermore, based on the difference in the catalytic performance and stability of different catalysts, the review summarizes the performance of non-noble metal SACs (such as Fe, Ni, Co, Mn, Cu, Sn, and Zn) with single metal sites in CO₂ reduction reaction. The discussion of the potential mechanisms is included. Finally, the review ends by presenting an outlook on the difficulties and possibilities inherent in this developing area of single atom electrocatalytic CO₂ reduction.