Energy structure and photocatalytic activity of niobates and tantalates containing Sn(II) with a 5s² electron configuration

SnNb₂O₆ (BG = 2.3 eV) containing Sn^2- with a 5s² electron configuration showed the photocatalytic activity for H₂ evolution from an aqueous methanol solution under visible light irradiation (λ > 420 nm) in the presence of a Pt cocatalyst. The energy structure calculation by the plane wave based density functional method revealed that the conduction and valence bands consisted of Nb4d and Sn5s orbitals, respectively. The valence band level consisting of the Sn5s orbitals was more negative than that consisting of O2p orbitals resulting in SnNb ₂O₆ being responsive to visible light.