Co single atom modulating the secondary coordination environment of Bi sites for boosting the adsorptive and catalytic capacity during CO2 photoreduction

In this work, a promising strategy was established to regulate the coordination environment of Bi active sites through metal atom doping. Interestingly, the doped Co in BiO quantum dots (QDs) are atomically dispersed in the second coordination shell, and can promote the hybridization and redistribution of atomic orbitals, thus improving the interaction with C 2p orbital in CO2 molecules. The Co single atom located at the secondary coordination shell changes the work function of BiO QDs, thereby facilitating the transfer of photogenerated electrons from Co to Bi active sites, and thus more long-lived electrons can take part in the CO2 reduction reaction. Additionally, the free energy calculations demonstrate that the existence of Co single atoms in secondary coordination environment is conducive to reduce the formation energy barriers as well as boost the stability of the intermediate *COOH, thus promoting the catalytic performance towards CO2 reduction.