Heteroepitaxial approach to explore charge dynamics across Au/BiVO₄ interface for photoactivity enhancement

Heterostructure provides a powerful route in manipulating electrical transport, optical response, electrolytic water splitting and water treatment of complex oxides. As a model for noble metal/ complex oxide heterostructures, we have successfully prepared Au/BiVO₄ (BVO) heterostructures in which the Au nanoparticles (NPs) with various sizes and densities were uniformly deposited on the {001} facets of epitaxial BVO thin films. The heterostructures exhibit significantly enhanced photoactivities in both dye degradation and electrolytic water splitting. By employing X-ray photoelectron spectroscopy, the energy band alignment of Au/BVO heterojunction suggests a charge separation at their interfaces, that can manipulate the photoexcited electron-hole pairs and photocatalytic efficiency of the heterostructures. Photogenerated carrier injection, which mainly affects the photoactivity of photocatalysis, was detected across Au/BVO interfaces by ultrafast dynamics spectroscopy. This study delivers a general approach to probe and understand the photochemistry of noble metal-complex oxide heterostructures for photoconversion applications.