Defect anchored single atomic Tin-nitrogen sites on graphene nanomesh for enhanced CO2 electroreduction to CO.

Developing Sn, nitrogen-doped carbon catalysts (Sn-NC) for efficient CO2 electroreduction (CO2RR) to CO remains a great challenge. Here, we employed a defective hierarchical porous graphene nanomesh to anchor the single atomic tin-nitrogen sites (A-Sn-NGM) for effective CO2 electroreduction. The synthesized A-Sn-NGM typically showed remarkable CO2RR activity towards CO production, which achieved a maximum CO Faradaic efficiency (FECO) of 98.7 % and a turnover frequency of 5117.4 h-1 at a potential of -0.6 V (vs. RHE). Further analysis proves that the increased activity to CO production of A-Sn-NGM derives from the enlarged roughness and enhanced intrinsic activity. Density-functional theory (DFT) calculations indicate that the adjacent carbon defects anchored Sn-Nx coordination sites can markedly inhibit the competing hydrogen evolution reaction (HER) and lower the energy barrier for the formation of *COOH intermediates as compared to bulk Sn-Nx sites without carbon defects. This work provides a reliable method by engineering the carbon support to improve the CO2RR performance for single-atom catalysts.