Heteroatom-Doped Asymmetric Metal-N x -C Single Atom Catalysts for Electrochemical CO 2 Reduction Reaction.

CO 2 utilization is one of the hottest research topics worldwide. As a class of newly emerging and promising catalysts for electrochemical CO 2 reduction (ECR) reaction, heteroatom-doped metal-N x -C single atom catalysts (M-N x -C SACs) attract extensive attentions. Nowadays, great progress, including structure modulation, identification of local coordination environment and ECR mechanism via advanced synthetic strategies, characterization techniques and theoretical calculations, have been achieved over heteroatom doped asymmetric M-N x -C SACs, which boost the ECR performances and deepen the understanding of ECR mechanism. In this context, we summarize recent progresses in heteroatom-doped asymmetric M-N x -C SACs, with emphasis on synthetic strategies and their applications in ECR reaction, along with current understanding on the ECR mechanisms both experimentally and theoretically. Finally, the challenges and perspectives for the heteroatom-doped asymmetric M-N x -C SACs towards ECR are proposed.