Facile Strategy for Synthesizing Non-Stoichiometric Monoclinic Structured Tungsten Trioxide (WO3−x) with Plasma Resonance Absorption and Enhanced Photocatalytic Activity

Shihao Chen,Yang Xiao,Yinhai Wang,Hui Zhao,Wei Xie,Wei Zhang,Zhengfa Hu

doi:10.3390/nano8070553

Shihao Chen, Yang Xiao + Show 5 more

Open Access

https://doi.org/10.3390/nano8070553

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Abstract

Oxygen vacancy defects play an important role in improving the light-capturing and photocatalytic activity of tungsten trioxide (WO3). However, the hydrogen treatment method that is commonly used to introduce oxygen vacancies is expensive and dangerous. Therefore, the introduction and control of oxygen vacancy defects in WO3 remains a challenge. Here, we demonstrated that oxygen vacancies could be successfully introduced into WO3−x while using a facile method through low temperature annealing in alcohol. The obtained WO3−x samples with optimal oxygen vacancies showed strong absorption of light, extending from the ultraviolet to the visible and near-infrared regions, and exhibits strong plasmon resonance from 400–1200 nm peaking at approximately 800 nm. When compared to pristine WO3, the photocatalytic activity of WO3−x was greatly improved in the ultraviolet and visible regions. This study provides a simple and efficient method to generate oxygen vacancies in WO3 for photocatalysis, which may be applied in the photoelectrochemical, electrochromic, and photochromic fields. Because oxygen vacancy is a common characteristic of metal oxides, the findings that are presented herein may be extended to other metal oxides.

Highlights

Semiconductor photocatalysis has attracted significant attention due to its promising applications in solar energy conversion, since the discovery of water splitting on a titanium dioxide (TiO2) photoanode in the 1970s [1]
Great efforts have been dedicated to enhancing the visible light absorption of large band gap metal oxides
The WO3 single crystal nanosheets were synthesized by a one-step template-free hydrothermal route [41]

Summary

Introduction

Semiconductor photocatalysis has attracted significant attention due to its promising applications in solar energy conversion, since the discovery of water splitting on a titanium dioxide (TiO2) photoanode in the 1970s [1]. Dye-sensitized and noble metal nanodot decorated TiO2 nanostructures were developed [4,5], forming heterojunctions with other semiconductors [6,7], and band gap narrowing was achieved via elemental doping in order to improve the conversion efficiency of metal oxide photoelectrodes. These methods modified the optical absorption coefficient and wavelength of the materials [8,9,10]. The WO3−x exhibited very strong visible and infrared light absorption, which significantly increased its photocatalytic activity

Preparation of the WO3 Nanosheets

Characterization

UV Light Photocatalytic Degradation

Visible Light Photocatalytic Degradation

Results and Discussion