Nickel-Doped Excess Oxygen Defect Titanium Dioxide for Efficient Selective Photocatalytic Oxidation of Benzyl Alcohol

In this study, a novel composite Ni-OTiO<sub>2</sub> was prepared by doping nickel and introducing excess oxygen defects in TiO<sub>2</sub>. The as-synthesized Ni-OTiO<sub>2</sub> particles were characterized by scanning electron microscopy, X-ray diffractino, transmission electron microscopy, Fourier transform infrared spectroscopy, differential reflectance spectroscopy, photoluminescence, photoelectrochemistry, and X-ray photoelectron spectroscopy. When employing Ni (1%)-OTiO<sub>2</sub> as photocatalyst, the conversion of benzyl alcohol (BA) was up to 93% by 1 h irradiation derived from a 300 W xenon lamp, which is ∼8-times higher than that using pure TiO<sub>2</sub>. Moreover, while being irradiated with the 300 W xenon lamp (using a filter, λ > 420 nm), the Ni (1%)-OTiO<sub>2</sub> conducted photocatalytic system can give 86% conversion of BA to benzaldehyde within 1 h. Specifically, during photocatalysis, a peroxo group and nickel ion act as the electron carrier, promoting the separation of the electron–hole pair. It is considered that the highly improved photocatalytic ability after modification of pure TiO<sub>2</sub> is ascribable to the synergistic effect of excess oxygen defects and nickel doping in TiO<sub>2</sub>.