Photocatalytic Water Splitting under Visible Light by Mixed-Valence Sn3O4

A mixed-valence tin oxide, (Sn2+)(2)(Sn4+)O-4, was synthesized via a hydrothermal route. The Sn3O4 material consisted of highly crystalline {010} flexes. The Sn3O4 material, when pure platinum (Pt) was used as a co-catalyst, significantly catalyzed water-splitting in aqueous solution under illumination of visible light (lambda > 400 nm), whereas neither Sn2+O nor Sn4+O2 was active toward the reaction. Theoretical calculations have demonstrated that the co-existence of Sn2+ and Sn4+ in Sn3O4 leads to a desirable band structure for photocatalytic hydrogen evolution from water solution. Sn3O4 has great potential as an abundant, cheap, and environmentally benign solar-energy conversion catalyst.