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 BVOac-BVOal homojunction with staggered band alignment. This architecture involves a built-in electric field that facilitating the electron-hole separation at the BVOac/BVOal interface. As a result, the BVOac-BVOal 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 BVOac-BVOal homojunction was achieved without incorporating any heteroatoms in this work. The remarkable PEC activity of the BVOac-BVOal 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.