Abstract
Tungsten trioxide (WO3) has been demonstrated to possess visible light photoactivity and presents a means of overcoming the UV-light dependence of photocatalysts, such as titanium dioxide. In this study, WO3 nanostructures have been synthesised by a hydrothermal method using sodium tungstate (Na2WO4·2H2O), sulphate precursors and pH as structure-directing agents and parameters, respectively. By altering the concentration of the sulphate precursors and pH, it was shown that different morphologies and phases of WO3 can be achieved. The effect of the morphology of the final WO3 product on the visible light photoactivity of ethylene degradation in the gas phase was investigated. In addition, platinum (Pt) was photodeposited on the WO3 structures with various morphologies to enhance the photocatalytic properties. It was found that the photocatalytic properties of the WO3 samples greatly depend on their morphology, chemical composition and surface modification. WO3 with a cuboid morphology exhibited the highest visible light photoactivity compared to other morphologies, while adding Pt to the surface improved the performance of certain WO3 structures.
Highlights
Volatile organic compounds (VOCs) are the group of airborne organic compounds capable of damaging human health and the environment
The W0 particles were yellow in colour and identified by X-ray diffraction (XRD) analysis to be a mixture of the monoclinic WO3 phase and the orthorhombic WO3·1⁄3H2O phase
WSA consists of nanoparticles with a size distribution from 30–100 nm and, from XRD was found to possess a pure monoclinic crystalline phase
Summary
Volatile organic compounds (VOCs) are the group of airborne organic compounds capable of damaging human health and the environment. Several methods, including chemical vapour deposition (CVD) [7], thermal evaporation [8], electrochemical techniques [9], a spray pyrolysis approach [10], template-mediated synthesis [11], the sol-gel process [12] and hydrothermal reactions [13], have been reported for WO3 nanostructure synthesis. Emphasis is placed on the influence of preparation conditions on the characteristics of WO3 nanostructures and, subsequently, on its capacity to photodegrade gas-phase ethylene using visible light as the energy source. Improvements in WO3 photoactivity, so as to counteract this limitation, may be achieved by closely controlling particle morphology [19] or by loading platinum (Pt) deposits on the surface. Pt loaded onto WO3 nanoparticles has been shown to enhance aqueous acetic acid mineralisation compared to bare WO3 photocatalysts under visible light illumination [21].
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