Preparation of α-SnWO4 hierarchical spheres by Bi3+-doping and their enhanced photocatalytic activity under visible light

Bi-doped α-SnWO4 porous spheres assembled by thin plates were prepared by a simple hydrothermal process without any template. The effects of Bi3+ ions on the microstructure and photocatalytic activity of α-SnWO4 were investigated. The doping of Bi can induce a shape transformation from nanoplates of pure α-SnWO4 to hierarchical spheres of Bi-doped samples. The photocatalytic activities of the as-prepared samples were evaluated by photocatalytic de-colorization of methyl orange (MO) under visible light irradiation. Bi-doped α-SnWO4 samples exhibit better photocatalytic property than pure α-SnWO4, and the optimal Bi-doping concentration is around 0.5 at%. The enhanced photocatalytic properties of Bi-doped α-SnWO4 spheres can be ascribed to the porous hierarchical structure and the introduction of defects induced by Bi-doping, which improve visible-light absorption and allow the efficient charge separation of the photogenerated electron-hole pairs. Bi-doped α-SnWO4 has a great potential in industrial water treatment due to its satisfactory recyclability and stability.