Fe and Ni co-doped TiO2 nanoparticles prepared by alcohol-thermal method: Application in hydrogen evolution by water splitting under visible light irradiation

Pure TiO2, single-doped and (Fe, Ni) co-doped TiO2 nanoparticles were successfully prepared by alcohol-thermal method with tetrabutyl titanate as the Ti source. The prepared samples were characterized by X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET) measurement, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), UV–visible spectroscopy (UV–vis) and photoluminescence spectroscopy (PL). UV–vis absorption indicates that the co-doped TiO2 exhibits a good absorption of visible light, and the optimal molar ratio of Fe and Ni to Ti is 5.0% and 4.0%, respectively. The photoluminescence spectroscopy indicates that the separation efficiency of photo-induced electrons and holes is improved by the co-doping method. The nano TiO2 samples possess pure anatase phase and doping TiO2 with metal ions can suppress the crystal growth of the particles. The particle sizes of 5.0% Fe–4.0% Ni/TiO2 are about 14 nm. The specific surface area of 5.0% Fe–4.0% Ni co-doped TiO2 is 98.35 m2/g while that of the un-doped is 43.13 m2/g. The photocatalytic activities of the catalysts were estimated by detecting the H2 evolution rate from water, and the average maximum H2 evolution rate was 361.64 μmol·h− 1·gcat− 1 (with a measured time of 6 h) using 5.0% Fe–4.0% Ni/TiO2 catalyst. The H2 evolution rate was detected in the mixture of ethanol and water under visible light irradiation (λ > 400 nm). Additionally, the mechanism of H2 evolution by water splitting is proposed.