Asymmetric Coordination Environment Engineering of Atomic Catalysts for CO 2 Reduction.

Single-atom catalysts (SACs) have emerged as well-known catalysts in renewable energy storage and conversion systems. Several supports have been developed for stabilizing single-atom catalytic sites, e.g., organic-, metal-, and carbonaceous matrices. Noticeably, the metal species and their local atomic coordination environments have a strong influence on the electrocatalytic capabilities of metal atom active centers. In particular, asymmetric atom electrocatalysts exhibit unique properties and an unexpected carbon dioxide reduction reaction (CO 2 RR) performance different from those of traditional metal-N 4 sites. This review summarizes the recent development of asymmetric atom sites for the CO 2 RR with emphasis on the coordination structure regulation strategies and their effects on CO 2 RR performance. Ultimately, several scientific possibilities are proffered with the aim of further expanding and deepening the advancement of asymmetric atom electrocatalysts for the CO 2 RR.