Preparation of Surface Dispersed WO₃/BiVO₄ Heterojunction Arrays and Their Photoelectrochemical Performance for Water Splitting

In this work, a surface dispersed heterojunction of BiVO₄-nanoparticle@WO₃-nanoflake was successfully prepared by hydrothermal combined with solvothermal method. We optimized the morphology of the WO₃ nanoflakes and BiVO₄ nanoparticles by controlling the synthesis conditions to get the uniform BiVO₄ loaded on the surface of WO₃ arrays. The phase composition and morphology evolution with different reaction precursors were investigated in detail. When used as photoanodes, the WO₃/BiVO₄ composite exhibits superior activity with photocurrent at 3.53 mA cm⁻² for photoelectrochemical (PEC) water oxidation, which is twice that of pure WO₃ photoanode. The superior surface dispersion structure of the BiVO₄-nanoparticle@WO₃-nanoflake heterojunction ensures a large effective heterojunction area and relieves the interfacial hole accumulation at the same time, which contributes to the improved photocurrents together with the stability of the WO₃/BiVO₄ photoanodes.