Facile preparation of Z-scheme WO3/g-C3N4 composite photocatalyst with enhanced photocatalytic performance under visible light

Visible-light-driven WO3/g-C3N4 composites photocatalysts were synthesized via a facile one-step simultaneously heating procedure with urea as the main precursor. These prepared catalyst samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), transmission electron microscopy (TEM), N-2 adsorption, ultraviolet-visible diffuse reflection spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and electrochemical impedance spectroscopy (EIS). The photocatalytic activity of the WO3/g-C3N4 composites was evaluated by the photo-degradation of Rhodamine B (RhB) under visible light irradiation. The results indicated that the composites with 25wt.% WO3 content exhibited highest photocatalytic activity compared to pure WO3, bare g-C3N4 and other WO3/g-C3N4 composites. The favorable photocatalytic activity of WO3/g-C3N4 composites was mainly attributed to the excellent surface properties, enhanced visible-light absorption and the desirable band positions. A possible Z-scheme photocatalytic mechanism was proposed based on structure and electrochemical characterizations results, which can well explain the enhanced migration rate of photogenerated electrons and holes in WO3/g-C3N4 heterojunctions. (C) 2016 Elsevier B.V. All rights reserved.