Synthesis of g-C3N4/BiVO4 and Its Photocatalytic Performance for Hydrogen Production

Abstract

In this study, ultrasonic hybridization was used to improve the photocatalytic efficiency and stability of the g-C3N4/BiVO4 photocatalyst, which was synthesized using Bi(NO3)3·5H2O and NaVO3 via the hydrothermal method to obtain BiVO4, and further modified by g-C3N4. Moreover, the obtained photocatalyst was studied using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller, ultraviolet–visible spectroscopy and electrochemical impedance spectroscopy. Subsequently, the photocatalytic performance for hydrogen production of the obtained photocatalyst was determined in a photocatalytic reactor under visible light, with methanol as the sacrificial agent and chloroplatinic acid as the promoter. The experimental results showed that the photocatalytic activity of BiVO4 considerably improved under visible light condition when its surface was modified with g-C3N4. When the amount of g-C3N4 was 5% of the amount of BiVO4, the hydrogen production rate was 53.25 μmol/h, which was 77.17 times higher than that of pure BiVO4. This improved performance can be attributed to the larger specific surface area, the better electron transfer efficiency and the electron–hole pair separation efficiency of g-C3N4/BiVO4. A possible mechanism model for the formation of g-C3N4/BiVO4 composite photocatalyst has also been proposed.