Visible-light-driven photocatalytic performance of a Z-scheme based TiO2/WO3/g-C3N4 ternary heterojunctions

Abstract

A ternary TiO2/WO3/g-C3N4 (TWG) hybrid photocatalyst was synthesised via pulsed laser ablation in liquids (PLAL) technique. The photocatalyst was characterised using different analytical techniques such as UV–vis spectroscopy, Scanning electron microscopy, Photoluminescence, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area analysis. While the TEM analysis revealed the anchoring of TiO2 and WO3-NPs on the g-C3N4 sheet, the crystal structure of the ternary system as observed in the XRD spectra contains the peaks of all the components materials, which indicate effective formation of TiO2/WO3/g-C3N4 nanocomposite. Methylene Blue dye (MB-dye) was employed as a model pollutant to assess the performance of the TiO2/WO3/g-C3N4 nanocomposite in the photocatalytic degradation experiment, under visible light irradiation using a 300 W xenon lamp. The results demonstrated that loading of TiO2/WO3 binary system with x-wt% (x = 5, 10, 15, 20) of g-C3N4, which serves as an interfacial mediator for proper separation and transfer of charges through the formation of heterojunction and Z-scheme with TiO2 and WO3 respectively, excellently enhanced their photocatalytic performance. The loading of g-C3N4 helps to increase the surface area of the ternary system for photocatalytic reaction, enhance the light absorption capacity in the visible region and thereby enhancing the photocatalytic performance of the system. The ternary system (nanocomposite) with optimal loading of 15 % g-C3N4 showed the highest photo-degradation efficiency (91.5 %) and rate constant (0.0215 min−1) which is about 3 times higher than those of their binary counterparts.