A facile solvothermal approach of novel Bi2S3/TiO2/RGO composites with excellent visible light degradation activity for methylene blue

Abstract

In this paper, novel photocatalyst Bi2S3/TiO2/RGO composites were successfully fabricated by a facile solvothermal method. During this process, TiO2 was coupled with Bi2S3 to generate Bi2S3 sensitized TiO2 nanoparticles, and graphene oxide (GO) was reduced to reduced graphene oxide (RGO), which was uniformly covered with plenty of Bi2S3 and TiO2. The as-prepared samples were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), specific surface areas (BET), X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL) spectroscopy. The results confirmed that Bi2S3 could act as an optical filter, which could be activated under visible light. And the introduction of Bi2S3 could improve the response of TiO2 nanoparticles for visible light. In addition, the Bi2S3/TiO2 in Bi2S3/TiO2/RGO composites had more uniform dispersion on the surface of graphene with less agglomeration in comparison with the Bi2S3/TiO2. Graphene can provide conductive electron channels for separation of the electrons and inhibit the recombination of electrons and holes. Furthermore, the photocatalytic activity of Bi2S3/TiO2/RGO composites was evaluated through the degradation of methylene blue (MB) under visible light irradiation. The Bi2S3/TiO2/RGO composites showed the highest photocatalytic activity among the referred photocatalysts, with about 3-fold increase in photocatalytic efficiency over TiO2 nanoparticles. The mechanism of high photocatalytic activity was also discussed.