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 CO 2 reduction (ECR) is of paramount importance. Herein, we report a single-atom Co-N-C catalyst (CoN 4 -CB) with a high CO Faradaic efficiency (FE CO , 98.7%) in ECR comparable to that of a similarly prepared NiN 4 -CB catalyst. Impressively, CoN 4 -CB demonstrates a CO turnover frequency of 27173 h −1 and a CO current density of −33.6 mA∙cm −2 at −0.76 V, 20.2 and 6.8 times higher than that of NiN 4 -CB, respectively. In a solar-driven ECR system composed of a Si solar cell and a flow cell, CoN 4 -CB shows a remarkably large current density of 98.3 mA∙cm −2 with an average FE CO of 92.1%. Theoretical calculations suggest that the energy barrier for *COOH formation largely decreases on CoN 4 sites compared with NiN 4 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. • CoN 4 -CB catalyst enables efficient ECR to CO. • CoN 4 -CB displays comparable selectivity to NiN 4 -CB but much enhanced activity. • An optimized solar driven system for ECR to CO at high current density. • DFT results well supported the experimental results.