Photoelectrochemical stability of WO3/Mo-doped BiVO4 heterojunctions on different conductive substrates in acidic and neutral media

Highlights: • Photoelectrochemical corrosion of WO₃/Mo-doped BiVO₄ heterojunctions. • Influence of acidic and neutral aqueous electrolytes on the photocorrosion process. • Effect of structure on the photoelectrochemical performance and photostability. • High performance of 3D-structured WO₃/Mo-doped BiVO₄ photoanode at low pH. Bismuth vanadate (BiVO₄) and tungsten trioxide (WO₃) are promising materials for photoelectrochemical (PEC) water splitting. To date, the heterojunction composed of both materials garners great attention due to the superior performance and the potential to capture visible light. However, the compatibility in different experimental conditions is limited by its low stability. Some factors which can impact the stability are pH of aqueous media, electrolytes, conductive substrates, and light irradiation. The mechanism of the corrosion process, which decays PEC performance as a function of time, has been studied. In this article, we prepared WO₃/Mo-doped BiVO₄ on a three-dimensional macroporous titanium (Ti) felt, which is a potential substrate for different types of PEC, and compare its stability with the heterostructure prepared on a conventional fluorine-doped tin oxide (FTO)-coated glass. The PEC performance and the stability of single layer WO₃, Mo-doped BiVO₄, and the heterojunction are investigated at low and moderate pH. The characterization and PEC measurements determined that pH has a significant effect on chemical dissolution and photocorrosion, directly impacting the stability of photocurrent generated from WO₃/Mo-doped BiVO₄ heterojunction in both substrate structures. Besides, WO₃/Mo-doped BiVO₄ on Ti felt shows higher and more stable PEC performance at low and moderate pH values.