Heterostructured WO₃-TiVO₄ thin-film photocatalyst for efficient photoelectrochemical water splitting

Photoelectrochemical water splitting via solar irradiation has garnered significant interest due to its potential in large-scale renewable hydrogen production. Heterostructure materials have emerged as an effective strategy, demonstrating enhanced performance in photoelectrochemical water-splitting applications compared to individual photocatalysts. In this study, to augment the performance of sprayed TiVO₄ thin films, a hydrothermally prepared WO₃ underlayer was integrated beneath the spray pyrolised TiVO₄ film. The consequent heterostructure demonstrated notable enhancements in optical, structural, microstructural attributes, and photocurrent properties. This improvement is attributed to the strategic deposition of WO₃ underlayer, forming a heterostructure composite electrode. This led to a marked increase in photocurrent density for the WO₃/TiVO₄ photoanode, reaching a peak of 740 μA/cm² at an applied potential of 1.23 V vs RHE, about nine-fold that of standalone TiVO₄. Electrochemical impedance spectroscopy revealed a reduced semicircle for the heterostructure, indicating improved charge transfer compared to bare TiVO₄. The heterostructure photoelectrode exhibited enhanced charge carrier conductivity at the interface and sustained stability over 3 h. The distinct attributes of heterostructure photoelectrode present significant opportunities for devising highly efficient sunlight-driven water-splitting systems.