Photocatalytic Water Splitting under Visible Light by Mixed-Valence Sn3O4

A mixed-valence tin oxide, (Sn2+)2(Sn4+)O4, was synthesized via a hydrothermal route. The Sn3O4material consisted of highly crystalline {110} flexes. The Sn3O4material, when pure platinum (Pt) was used as a co-catalyst, significantly catalyzed water-splitting in aqueous solution under illumination of visible light (λ > 400 nm), whereas neither Sn2+O nor Sn4+O2was active toward the reaction. Theoretical calculations have demonstrated that the co-existence of Sn2+and Sn4+in Sn3O4leads to a desirable band structure for photocatalytic hydrogen evolution from water solution. Sn3O4has great potential as an abundant, cheap, and environmentally benign solar-energy conversion catalyst.