Synthesis of Single Phase Sn3O4: Native Visible-Light-Sensitive Photocatalyst with High Photocatalytic Performance for Hydrogen Evolution

A visible light sensitive photocatalyst, Sn3O4, was synthesized by optimizing hydrothermal reaction conditions. The single phase of Sn3O4 was obtained by the optimal condition ((C6H5O7)(3)-/Sn2+ = 2.5, pH= 5.5, heating time= 6 h, filtration and NaOH washing). The single phase Sn3O4 significantly catalyzed hydrogen evolution in aqueous solution in the presence of sacrifice agent under irradiation of visible light (lambda > 420 nm), even without Pt co-catalyst. Pt co- catalyst was critical for Sn3O4 material to exhibit higher photocatalytic activity, so far in this study. The apparent quantum yield was 0.2% for single phase Sn3O4 and 1.5% for Pt loaded-Sn3O4, competitive to that of visible-lightsensitive doped metal oxide and (oxy) nitrides photocatalyst. The band edge positions of Sn3O4 were estimated from the UV-Vis absorption spectra and the valence band XPS spectra. The enhanced hydrogen evolution of the single phase Sn3O4 is attributed to the desirable band gap and band edge position for overall water splitting in visible light, which originate from co- existence of Sn4+ with Sn2+ in Sn3O4.