Photocatalytic properties of SnS2/SnO2 nanocomposite prepared by thermal oxidation of SnS2 nanoparticles in air

An alternative in situ chemical method, which was based on thermal oxidation of SnS2 nanoparticles in air at 300 °C for 3 h, was proposed for the preparation of SnS2/SnO2 nanocomposite (SnS2/SnO2-TO). The photocatalytic properties of SnS2/SnO2-TO were tested by the reduction of aqueous Cr(VI) under visible-light (λ > 420 nm) irradiation, and compared with those of SnS2 nanoparticles, SnO2 nanoparticles and SnS2/SnO2-PM (which denotes the physically mixed SnS2/SnO2 nanocomposite with the same composition as SnS2/SnO2-TO). Besides, the effects of the coexistence of some organic compounds (e.g., phenol, rhodamine B (RhB) and methyl orange (MO)) on SnS2/SnO2-TO-mediated photocatalytic reduction of aqueous Cr(VI) were also studied. It was observed that (i) SnS2/SnO2-TO not only displayed higher visible-light-activated photocatalytic activity than SnS2, SnO2 and SnS2/SnO2-PM, but also displayed good reusability in the reduction of aqueous Cr(VI); and (ii) the coexistence of phenol and RhB enhanced the photocatalytic reduction of Cr(VI), whereas the coexistence of MO retarded the photocatalytic reduction of Cr(VI) over SnS2/SnO2-TO. The reasons accounting for the photocatalytic results were also discussed.