Enhanced photocatalytic activity of indium and nitrogen co-doped TiO2–Pd nanocomposites for hydrogen generation Original Research Article

Indium and nitrogen co-doped TiO2, indium- or nitrogen-doped TiO2 and undoped TiO2 were synthesized by polyol method and studied their photocatalytic activity for hydrogen generation from water. Crystalline nanoparticles of predominantly anatase phase of TiO2 were obtained by this method. A clear red shift of the absorption edge and stronger absorption in the visible region was observed for indium and nitrogen co-doped TiO2 compared to the other samples. The presence of bonded nitrogen in the N-doped samples was evidenced from their N 1s X-ray photoelectron spectra. Photocatalytic activity for hydrogen generation using sunlight type radiation showed enhanced activity for the doped samples compared to pristine TiO2. The photocatalytic activity of different samples decreased in the following order: N and In co-doped TiO2 > In-doped TiO2 > N-doped TiO2 > undoped TiO2. The enhanced photocatalytic activity of the In and N co-doped TiO2 for hydrogen generation is attributed to the enhanced light absorption resulting from the narrowing of the band gap caused by the contribution of 5s5p orbitals of In to the conduction band and 2p orbitals of N to the valence band of TiO2. A pronounced enhancement of photocatalytic activity was observed for all catalysts when Pd metal was present as co-catalyst due to the efficient separation of photogenerated charge carriers in this nanocomposite system.