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

Abstract

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 (E_f) 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.