n-Type doping of BiVO4 with different F-doped concentrations for improving the electronic character of BiVO4 as a photoanode nanomaterial for solar water splitting: a first-principles study

Atom doping has been realized as an effective way to improve the photocatalytic performance of the most promising photoanode material, BiVO4, but the effects of doping mass concentration still need to be explored. In this work, the effects of F-doping with different doping mass concentrations (1%, 2%, 5%, 10%, 15%, and 20%) on the electronic character of BiVO4 were examined theoretically using density functional theory (DFT) calculations. The thermal stability of BiVO4 with different F-doped mass concentrations was confirmed using formation energy (Ef) calculations though F-doped BiVO4 becomes harder as the mass concentration of induced dopants increases. n-Type doping effects on the electronic character of BiVO4 were observed upon F-doping, leading to the energy level of CBM shifting far away from the Fermi level and giving F-doped BiVO4 metallic character. Moreover, a linear relationship between the frontier energy level shifts and the total charge transfer amounts from doped F atoms to other atoms involved in F-doped BiVO4 was observed, which means the oxidizing capacity of the VBM is increased and the reducing capacity of the CBM is decreased upon increased F-doped mass concentration. Moreover, the recombination of photogenerated electron-hole pairs is suppressed by F-doping strategies, which will not change a lot with the increased F-doped mass concentration. This means atom doping is an effective strategy to improve the photocatalytic efficiency of the BiVO4, but the number of atoms introduced into BiVO4 should be appropriate.