Synergistic interaction of Z-scheme TiO2/g-C3N4 photocatalyst and peroxymonosulfate for improving the photocatalytic efficiency of Rhodamine B

Abstract

A Z-scheme TiO2/g-C3N4 heterostructure system was used to activate peroxymonosulfate (PMS) for the photocatalytic degradation of Rhodamine B (RhB). The Z-scheme TiO2/g-C3N4 heterojunction photocatalysts were successfully synthesized by using a simple impregnation method. The structure and surface morphology of the samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), X-Ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical and electrochemical properties were characterized by UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) electrochemical impedance spectroscopy (EIS).The results indicated that the Z-scheme heterojunction between TiO2 and g-C3N4 was successful established and the optimal photocatalytic activity was achieved when the mass ratio of TiO2 to g-C3N4 is 10:1. The degradation rate of RhB (20 mg/L, 50 mL) was 82.79% within 120 min simulated sunlight irradiation. After adding PMS to 10% TiO2/g-C3N4 heterojunction photocatalysts, the reaction rate constant (k) of the TiO2/g-C3N4-PMS system is about 11.39 times as large as that with 10% TiO2/g-C3N4 system. Moreover, the free radical trapping experiments results demonstrated that h+ and SO4−· were the main active species in the TiO2/g-C3N4-PMS system.