Preparation of a novel Cd2Ta2O7 photocatalyst and its photocatalytic activity in water splitting

Cd2Ta2O7, which showed high photocatalytic activity for overall water splitting, was synthesized by sol–gel method. Its maximum activity increased from 46.2 μmol-H2/h and 23.0 μmol-O2/h into 173.0 μmol-H2/h and 86.3 μmol-O2/h when 0.2 wt.% NiO was loaded as co-catalyst. The band structure of Cd2Ta2O7 was calculated by a plane-wave-based density functional theory (DFT). The valence band is mainly formed by O 2p AO's, and the conduction band predominantly consists of Ta 5d, O 2p and Cd 5s5p AO's. Cd atoms endue new features different from other tantalates, and its effect on the band structure of Cd2Ta2O7 was discussed.

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► A novel Cd2Ta2O7 photocatalyst was synthesized by sol–gel method.
► It contains three-dimensional framework formed by TaO6 and CdO8 polyhedra.
► It could split pure water into H2 and O2 in a nearly stoichiometric ratio.
► Its H2 production rate increased clearly when 0.2% NiO was loaded on its surface.
► The p–d repulsion of O 2p and Cd 4d orbits narrows the band gap.