A facile synthesis of g-C3N4/TiO2 hybrid photocatalysts by sol–gel method and its enhanced photodegradation towards methylene blue under visible light

Abstract

The g-C3N4/TiO2 hybrid photocatalysts were synthesized through a modified sol–gel technique with varying the weight ratio of g-C3N4 under facile conditions. The microstructure and interface properties of the obtained photocatalysts were systematically studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR) and UV–visible diffused reflectance spectroscopy (UV–vis DRS). It is indicated that the heterojunction between g-C3N4 and TiO2 formed and the TiO2 nanoparticles well dispersed on g-C3N4 sheets. Among as synthesized hybrid photocatalysts, the g-C3N4/TiO2-80% sample exhibited the highest photocatalytic activity under visible light irradiation using methylene blue as the target pollutant. Compared with pure g-C3N4 and TiO2, the g-C3N4/TiO2-80% hybrid photocatalyst exhibited enhanced visible-light photoactivity, which is around 3.5 times as high as that of the pure g-C3N4. The enhancement of the g-C3N4/TiO2 hybrid photocatalysts can be attributed to the relatively higher adsorption capacity and effective separation of photogenerated electron–hole pairs. The g-C3N4/TiO2 hybrid photocatalysts exhibited stable photocatalytic performance with a very low activity loss after going through five cycles, which shows that it is a promising material for the photodegradation of dyes in wastewater.