First-principles studies of monolayers MoSi2N4 decorated with transition metal single-atom for visible light-driven high-efficient CO2 reduction by strain and electronic engineering

Abstract

Solar-driven CO2 reduction into value-added hydrocarbons could promote CO2 utilization and solve related environmental issues, while the key lies in the modulation of the active site's orbital electronic state. By performing first-principles calculations, we systematically explore MoSi2N4 decorated with 3d and 4d period transition metal single atoms (TMSAs) as efficient CO2 reduction photocatalysts and find that product selectivity is highly correlated with the d-band center of TMSAs. Compressive and tensile strains in mutually perpendicular directions are introduced in the horizontal plane to improve the catalytic performance. After filtering, V, Mn, and Ni were found to be the best TMSAs for CO, HCOOH, and CH4 production, respectively. Ni/MoSi2N4 under −6% tensile strain exhibited the lowest CO2 reduction limiting potential (UL) of 0.24 V. Notably, the time-dependent ab initio nonadiabatic molecular dynamics simulations were carried out to elucidate the photogenerated electron transport properties, where the photo-generated electrons can be efficiently transferred from MoSi2N4 to TMSAs active sites. We also identify that the applied strains affect the CO2 reduction performance by modulating the d-band center and valence electrons. These findings provide pioneering design schemes of precisely tailored photocatalytic systems for CO2 reduction under visible light.