S and N coordinated single-atom catalysts for electrochemical CO2 reduction with superior activity and selectivity

As the energy crisis and global warming become ever more serious, the electrochemical reduction of carbon dioxide (CO2RR) using single-atom catalysts (SAC) is a potential strategy to solve these problems by converting notorious CO2 into high value-added products. The electronic structures and the catalytic activity of SAC can be adjusted through changing the coordination environment. In this paper, 28 TM@SxNy SACs (TM = Fe, Co, Ni, Cu; x + y = 4) are constructed and the CO2RR performances toward C1 products are exploited. The calculations based on spin-polarized density functional theory (DFT) show that Cu@S3N1 has the best catalytic performance toward CO, CH3OH and CH4, with the favorable limiting potentials of-0.20 V,-0.36 V, and-0.36 V, respectively. Fe@S1N3 exhibits the best catalytic activity and selectivity toward HCOOH, with the limiting potential of-0.25 V. Electronic structure analysis reveals the catalytic origin of excellent Cu@S3N1 SAC toward CO product. SxNy coordination can partially weaken the scaling relationship between *COOH and *CO, especially for S3N1. Furthermore, the solvation effect and the selectivity of Cu@S3N1 and Fe@S1N3 under the applied potential are illustrated. The results provide a theoretical reference to regulate the CO2RR activity using coordinated SAC.