Photoelectrochemical (PEC) water splitting with metal oxides photoelectrodes is a promising renewable technology because of their good performance for light harvesting and stability as well as good properties such as naturally earth-abundant, harmless and economical. BiVO4 has been regarded as a major metal oxide material in the PEC photoanode due to the suitable band gap for efficient light absorption and advantage of solar-to-hydrogen conversion efficiency. However, the PEC performance of this single absorber material is limited due to its charge recombination in bulk, interface and surface derived by poor carrier diffusion property, electrical conductivity and water oxidation kinetics. Until now, many attempts of junction of two materials such as BiVO₄/WO₃, BiVO₄/ZnO or BiVO₄/Bi₂WO₆ to form a type-II heterojunction has been introduced to be a feasible mean to improve the charge separation and transport efficiencies.

In this study, we have modified the BiVO₄ single absorber with Zn and Mo doping and introduced the type-II homojunction BiVO₄ photoanode for efficient PEC water splitting via a facile solution method. Interestingly, the Zn and Mo doping treatment let BiVO₄ thin-film change the Fermi level and form the staggered band alignment. It is helpful to enhance the charge separation in bulk and charge transfer in surface of BiVO₄ due to the interference of surface trapping of photogenerated charge carriers with type-II homojunction followed by the enhancement of PEC water splitting performances.