A study of photocatalytic and photoelectrochemical activity of as-synthesized WO3/g-C3N4 composite photocatalysts for AO7 degradation

Abstract

Herein, we have examined the effect of tungsten trioxide (WO3) doping in graphitic carbon nitride (g-C3N4) photocatalysts towards photodegradation of organic pollutant in aqueous medium. A sequence of visible light driven WO3/g-C3N4 composites were synthesized at various mole ratios (1, 2, 3 and 5%) of WO3 into g-C3N4 via simple and short-time wet-impregnation method. The fabricated photocatalytic materials were investigated by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, UV–vis diffuse reflection spectroscopy (DRS), photoluminescence (PL) and scanning electron microscopy (SEM). The photocatalytic performance of the fabricated photocatalysts were assessed by the degradation of acid orange 7 (AO7) in visible-light illumination. The WO3/g-C3N4 composites were found to be exhibit an improved visible-light induced photocatalytic performances compared to the pure WO3 and g-C3N4. However, among the different composites, the optimized 3 wt% WO3/g-C3N4 composite has shown complete (100%) degradation efficiency of AO7 after 75 min which is superior than the pure g-C3N4. This synergistic enhancement might be credited to its increased light absorption in visible-light region and the photoexcited electron transfer from g-C3N4 to WO3 catalyst surface and enhanced charge separation efficiency. Additionally, the photo-electrochemical measurements of 3 wt% WO3/g-C3N4 composite has exhibited a quicker migration of the photo-excited charge-carriers. The radical scavenging studies inferred that the O2− are the key species accountable for the degradation of AO7 for fabricated WO3/g-C3N4 composite materials. Hence, the higher photocatalytic activity, long-term stability and recyclability of WO3/g-C3N4 composite has displayed it is a auspicious material for the photocatlytic degradation of organic contaminant applications.