Characterization of N-doped TiO2 nanoparticles supported on SrTiO3 via a sol–gel process

A heterojunction photocatalyst that efficiently enhanced hydrogen production from an aqueous solution containing a sacrificial reagent under solar irradiation was developed by growing N-doped TiO2 on SrTiO3 via a sol–gel process. The effect of N-doped TiO2 combined with SrTiO3 on the heterojunction properties was studied. The heterojunction characterization results indicated that the coupling of SrTiO3 with N-doped TiO2 enhanced the visible-light-absorption range because N-doped TiO2 acted as photosensitizer. In addition, N-doped TiO2 coated on SrTiO3 prevented particle agglomeration, providing the heterojunction materials with finer crystals of anatase TiO2 and larger specific surface area than the theoretical values. However, when the SrTiO3/N-doped TiO2 weight ratios were increased to over 10 %, the material increasingly showed SrTiO3-like properties, which gradually decreased the solar-energy-absorption efficiencies, S BET values,, and photoactivity. At the 5 % weight ratio of SrTiO3/N-doped TiO2, the photocatalytic H2 production rates of the heterojunction were significantly increased by up to 94.2 %, which could be ascribed to the efficient electron/hole separation, charge migration from the photocatalyst interior to the surface, absorption range of visible light, and prevention of particle agglomeration.