Synthesis of a visible-light active V2O5-g-C3N4 heterojunction as an efficient photocatalytic and photoelectrochemical material

A new V2O5-g-C3N4 nanocomposite was synthesized via a wet impregnation method using V2O5 and g-C3N4, obtained from citric acid and urea. The phase purity, crystallite size and strain were ascertained by powder X-ray diffraction (XRD) analysis. Furthermore, the synthesized photocatalysts were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflection spectroscopy (DRS) and photoluminescence spectroscopy (PL). The efficiency of the photocatalysts was evaluated by the photodegradation of direct red 81 (DR81), a target textile pollutant, under visible light irradiation. The photocatalytic experiments demonstrated that the V2O5-g-C3N4 composites showed much better photocatalytic degradability of DR81 than bulk V2O5 and g-C3N4, when used individually. The enhancement of photocatalytic degradation is attributed to the efficient charge carrier separation of photogenerated electron-hole pairs. PL and electrochemical impedance spectroscopic (EIS) results also support the above statement. Different mol% ratios (1, 2 and 3%) of V2O5 loaded composites have been prepared and a 1% loaded composite was found to show optimal efficiency. A possible mechanism has been proposed for the photocatalytic degradation using V2O5-g-C3N4.