Visible-light-induced water splitting on a hierarchically constructed Z-scheme photocatalyst composed of zinc rhodium oxide and bismuth vanadate

Abstract

Precise control of the interface in a solid-state heterojunction Z-scheme photocatalyst is important for achieving the intended photocatalytic activity. Herein, we have designed a photocatalyst with a hierarchical structure by photodepositing gold (Au) on the (040) facet of decahedral bismuth vanadate (BiVO₄) and then loading zinc rhodium oxide (ZnRh₂O₄) on the Au surface. Owing to the facet-dependent charge separation property of the decahedral BiVO₄, photoexcited electrons in BiVO₄ accumulate at the (040) facet and then transfer to Au, which acts as a solid electron mediator, to combine with holes of ZnRh₂O₄. Utilizing the thus-constructed Z-scheme photocatalyst (ZnRh₂O₄/Au/BiVO₄), the simultaneous liberation of hydrogen (H₂) and oxygen (O₂) from water at a molar ratio of 2 : 1 was achieved under irradiation with visible light up to a wavelength of 540 nm, whereas neither H₂ nor O₂ was produced when Au was deposited randomly on the BiVO₄ surface. This study provides insight into the rational design of a solid-state Z-scheme photocatalyst using facet-controlled nanoparticles to enhance photocatalytic activity.