  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.
