Boosting the photoelectrochemical performance of bismuth vanadate photoanode through homojunction construction

The photoelectrochemical (PEC) performance of bismuth vanadate (BiVO₄) suffers from sluggish charge mobility and substantial charge recombination losses due to its intrinsic defect. To rectify the problem, we developed a novel approach to prepare an n-n⁺ type II BVO_ac-BVO_al homojunction with staggered band alignment. This architecture involves a built-in electric field that facilitating the electron-hole separation at the BVO_ac/BVO_al interface. As a result, the BVO_ac-BVO_al homojunction shows superior photocurrent density up to 3.6 mA/cm² at 1.23 V vs. reversible hydrogen electrode (RHE) with 0.1 M sodium sulfite as the hole scavenger, which is 3 times higher than that of the single-layer BiVO₄ photoanode. Unlike the previous efforts that modifying the PEC performance of BiVO₄ photoanodes through incorporating heteroatoms, the highly-efficient BVO_ac-BVO_al homojunction was achieved without incorporating any heteroatoms in this work. The remarkable PEC activity of the BVO_ac-BVO_al homojunction highlights the tremendous importance of reducing the charge recombination rate at the interface by constructing the homojunction and offers an effective strategy to form the heteroatoms-free BiVO₄ thin film as an efficient photoanode material for practical PEC applications.