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

In this paper, novel photocatalyst Bi 2 S 3 /TiO 2 /RGO composites were successfully fabricated by a facile solvothermal method. During this process, TiO 2 was coupled with Bi 2 S 3 to generate Bi 2 S 3 sensitized TiO 2 nanoparticles, and graphene oxide (GO) was reduced to reduced graphene oxide (RGO), which was uniformly covered with plenty of Bi 2 S 3 and TiO 2 . 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 Bi 2 S 3 could act as an optical filter, which could be activated under visible light. And the introduction of Bi 2 S 3 could improve the response of TiO 2 nanoparticles for visible light. In addition, the Bi 2 S 3 /TiO 2 in Bi 2 S 3 /TiO 2 /RGO composites had more uniform dispersion on the surface of graphene with less agglomeration in comparison with the Bi 2 S 3 /TiO 2 . Graphene can provide conductive electron channels for separation of the electrons and inhibit the recombination of electrons and holes. Furthermore, the photocatalytic activity of Bi 2 S 3 /TiO 2 /RGO composites was evaluated through the degradation of methylene blue (MB) under visible light irradiation. The Bi 2 S 3 /TiO 2 /RGO composites showed the highest photocatalytic activity among the referred photocatalysts, with about 3-fold increase in photocatalytic efficiency over TiO 2 nanoparticles. The mechanism of high photocatalytic activity was also discussed.