Easy Synthesis of BiVO₄ for Photocatalytic Overall Water Splitting

Developing a photocatalyst system to generate hydrogen from water is a topic of great interest for fundamental and practical importance. In this study, we develop a new Z-scheme photocatalytic system for overall water splitting that consists of Rh/K₄Nb₆O₈ for H₂ evolution, Pt/BiVO₄ for O₂ evolution, and I^-/IO₃ ^- for an electron mediator under UV light irradiation. The oxygen evolution photocatalyst BiVO₄ was prepared by the microwave-assisted hydrothermal method. The method is fast and simple, as compared to conventional hydrothermal synthesis. The catalysts were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV-visible spectroscopy. The photocatalytic water splitting is investigated in (i) aqueous AgNO₃ as sacrificial electron scavengers and (ii) a Z-scheme photocatalytic water splitting system. The BiVO₄ photocatalysts prepared by the microwave-assisted hydrothermal method not only showed a very high oxygen evolution rate (2622 μmol g^-1 h^-1) of water splitting reaction in an aqueous AgNO₃ solution but also achieved a high H₂ evolution rate (340 μmol g^-1 h^-1) and O₂ evolution rate (172 μmol g^-1 h^-1) in a Z-scheme overall water splitting system.