Highly efficient water purification by WO3-based homo/heterojunction photocatalyst under visible light

Abstract: Bandgap engineering has attracted increasing interest in the field of semiconductive materials with specific electrical and optical characteristics for various applications, such as solar energy harvesting, energy-related applications, and photocatalysts. Here, we propose a novel and facile method to obtain a combination of type-II structure and Ohmic contact by the fabrication of WO3/Ti-WOx/TiHyOz homo/heterojunction on a WO3 photocatalyst using ball milling. The morphology and structural characterizations of the material are obtained using UV-vis, SEM/EDS, XRD, Raman spectroscopy, and XPS. It is revealed that titanium hydride (TiH2) facilitates simultaneous WO3 reduction and cation doping, which generates intervalent W ions (W5+, W4+) with oxygen deficiency, leading to the formation of new band structures at the WO3/Ti-WOx/TiHyOz interface. As a result, the homo/heterojunction significantly extends light absorption above 400 nm and facilitates the spatial separation of photoexcited carriers, which significantly enhances the photocatalytic performance to degrade azo-dye water pollutants under visible light irradiation.