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

TL;DR

This study develops a WO3-based homo/heterojunction photocatalyst with enhanced visible light absorption and pollutant degradation efficiency through bandgap engineering and structural optimization.

Contribution

It introduces a novel fabrication method for WO3/Ti-WOx/TiHyOz homo/heterojunctions that improve photocatalytic performance under visible light.

Findings

Extended light absorption above 400 nm.

Significantly improved degradation of azo-dye pollutants.

Enhanced spatial separation of photoexcited carriers.

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.