Enhanced photocatalytic activity of TiO2 nanoparticles using SnS2/RGO hybrid as co-catalyst: DFT study and photocatalytic mechanism.

Graphene-semiconductor nanocomposites, considered as one of the most promising noblemetal-free photocatalysts, have shown remarkable performance and drawn significant attention in the field of photocatalytic reaction using solar energy, due to the excellent physicochemical properties of graphene. Here, a facile and novel method called liquid-exfoliation and solvethermal method was used for preparing TiO 2 /SnS 2 /RGO nanocomposite with intimate hetero-interface. Under visible-light irradiation, the TiO 2 /SnS 2 /RGO nanocomposite showed high photoactivity for the degradation of Rhodamine B (RhB). The positive synergistic effect is emerged between these layered SnS 2 and RGO components, which contributes to the enhanced photoactivity of TiO 2 nano-particles through reducing the recombination of photogenerated electron/hole pairs, enhancing the rate of electron-transfer and providing more reaction active sites for the degradation of dye molecules. The coupling formation of TiO 2 , SnS 2 and RGO at the interface of composite photocatalyst was investigated by density functional theory (DFT) method in a molecular cluster level and the calculations results showed that the firm structures could be formed at the interfaces of TiO 2 nanoparticles and SnS 2 /RGO. and Active component analysis showed that the synergy of various components containing ·O 2 − , e − , OH was predicted to determine the degradation process. The photocatalytic mechanism was also discussed and Z-scheme electron-transfer was predicted as the charge-transfer type of TiO 2 /SnS 2 on RGO. [ABSTRACT FROM AUTHOR]