Three-Dimensional TiO2 Structures Incorporated with Tungsten Oxide for Treatment of Toxic Aromatic Volatile Compounds

Abstract

This study assessed 3D WO 3 -TiO 2 nanoflowers (WTNF) synthesized by a combined hydrothermal-ultrasonication-impregnation method for their applicability to the treatment of aromatic volatile compounds under visible-light illumination. The scanning electron microscopy exhibited the formation of 3D structures in the prepared WTNF samples. The X-ray diffraction patterns and energy dispersive X-ray results indicated a successful incorporation of WO 3 into TNF structures. The UV-visible spectroscopy showed that the prepared WTNF samples can be functioned under visible light irradiation. The output-to-input concentration ratios of toluene and o-xylene with WTNF samples were lower than those of TiO 2 nanoflowers. These findings were illustrated on the basis of charge separation ability, adsorption capability, and light absorption of the sample photocatalysts. The input-to-output concentration ratios of the target chemicals were lowest for 10 M NaOH and highest for 5 M NaOH. The photocatalytic degradation efficiencies of WTNF sample photocatalysts increased with increasing WO 3 content from 0.1% to 1.0%, and dropped gradually with increasing WO 3 content further to 4.0%. Light-emitting-diodes (LEDs) are a more highly energy-efficient light source compared to a conventional lamp for the photocatalytic degradation of toluene and o-xylene, although the photocatalytic activity is higher for the conventional lamp.

Sonochemical Synthesis of Ce-doped TiO2 Nanostructure: A Visible-Light-Driven Photocatalyst for Degradation of Toluene and O-Xylene

“…Consequently, the enhanced performance of the Ce-doped TiO 2 photocatalyst for the photodecomposition of toluene and o-xylene under the visible-light illumination could also be ascribed to the above-mentioned reaction mechanism. In this study, according to Lee and Jo [41], the reaction mechanism could be modified as follows:Ce-doped TiO 2 + visible light → e − + h + ,…”

“…The photocatalytic degradation experiments were conducted using a homemade reactor system similar to that used in our previous work [41], which is displayed in Figure 1. Major component parts of the reactor system included a high purity air cylinder for air supply, a water bath for moisture supply, a thermal chamber for mixing of air and standard substrates, a syringe pump for automatic injection of model toluene and o-xylene gases, gas flowmeters for stream flow rates measurement, a 3-way control valve for sampling gaseous target compounds, and a photoreactor (Pyrex tube with an inner diameter of 3.8 cm and a volume of 133 cm 3 ) with an 8 W conventional daylight lamp (λ = 400–700 nm) or 0.32 W white (λ = 450 nm) or 0.32 W violet (λ = 400 nm) LEDs as a light source.…”

Methane conversion and hydrogen production over TiO2/WO3/Pt heterojunction photocatalysts

“…Different works have also shown a significant improvement in charge transfer between TiO 2 and WO 3 , reaching better photocatalytic performances when the WO 3 concentration is less than 1%. 42,43 It has been demonstrated that higher WO 3 content increases the concentration of recombination centers for electron/hole pairs, contributing to lowering the photoactivity of TiO 2 -WO 3 -based photocatalysts. 44 Kara ´csonyi and co-workers 45 showed that significant differences in the photocatalytic performance of the TiO 2 /WO 3 /(Pt or Au) photocatalysts towards oxalic acid degradation were observed only through the position of the noble metal, if the co-catalyst is deposited on TiO 2 or on WO 3 .…”

Enhanced photocatalytic performance of tungsten-based photocatalysts for degradation of volatile organic compounds: a review

“…Doping hybrid WO 3 with other semiconductor to form a heterojunction is well-investigated to be an effective way for improving the separation efficiency of the photo-generated charges or extending the spectral response to full light region [49,50].…”