Photocatalytic Water Splitting for Hydrogen Production with Gd(2)MSbO(7) (M = Fe, In, Y) Photocatalysts under Visible Light Irradiation

Novel photocatalysts Gd(2)FeSbO(7), Gd(2)InSbO(7) and Gd(2)YSbO(7) were synthesized by the solid state reaction method for the first time. A comparative study about the structural and photocatalytic properties of Gd(2)MSbO(7) (M = Fe, In, Y) was reported. The results showed that Gd(2)FeSbO(7), Gd(2)InSbO(7) and Gd(2)YSbO(7) crystallized with the pyrochlore-type structure, cubic crystal system and space group Fd3m. The lattice parameter a for Gd(2)FeSbO(7), Gd(2)InSbO(7) or Gd(2)YSbO(7) was 10.276026 Å, 10.449546 Å or 10.653651 Å. The band gap of Gd(2)FeSbO(7), Gd(2)InSbO(7) or Gd(2)YSbO(7) was estimated to be 2.151 eV, 2.897 eV or 2.396 eV. For the photocatalytic water-splitting reaction, H(2) or O(2) evolution was observed from pure water with Gd(2)FeSbO(7), Gd(2)InSbO(7) or Gd(2)YSbO(7) as catalyst under visible light irradiation (wavelength > 420 nm). Moreover, H(2) or O(2) also spilt by using Gd(2)FeSbO(7), Gd(2)InSbO(7) or Gd(2)YSbO(7) as catalyst from CH(3)OH/H(2)O or AgNO(3)/H(2)O solutions under visible light irradiation (λ > 420 nm). Gd(2)FeSbO(7) showed the highest activity compared with Gd(2)InSbO(7) or Gd(2)YSbO(7). At the same time, Gd(2)InSbO(7) showed higher activity compared with Gd(2)YSbO(7). The photocatalytic activities were further improved under visible light irradiation with Gd(2)FeSbO(7), Gd(2)InSbO(7) or Gd(2)YSbO(7) being loaded by Pt, NiO or RuO(2). The effect of Pt was better than that of NiO or RuO(2) for improving the photocatalytic activity of Gd(2)FeSbO(7), Gd(2)InSbO(7) or Gd(2)YSbO(7).