A promising single-atom Co-N-C catalyst for efficient CO2 electroreduction and high-current solar conversion of CO2 to CO

Excavating highly efficient M-N-C electrocatalysts for electrochemical CO2 reduction (ECR) is of paramount importance. Herein, we report a single-atom Co-N-C catalyst (CoN4-CB) with a high CO Faradaic efficiency (FECO, 98.7%) in ECR comparable to that of a similarly prepared NiN4-CB catalyst. Impressively, CoN4-CB demonstrates a CO turnover frequency of 27173 h-1 and a CO current density of -33.6 mA center dot cm- 2 at -0.76 V, 20.2 and 6.8 times higher than that of NiN4-CB, respectively. In a solar-driven ECR system composed of a Si solar cell and a flow cell, CoN4-CB shows a remarkably large current density of 98.3 mA center dot cm- 2 with an average FECO of 92.1%. Theoretical calculations suggest that the energy barrier for *COOH formation largely decreases on CoN4 sites compared with NiN4 sites, leading to a low onset potential and high activity for CO production. This work will boost the development of efficient M-N-C electrocatalysts and further practical application of solar-driven ECR system.