Study of the Photocatalytic Performance of Oxygen-deficient TiO2 Active in Visible Light

Oxygen-deficient titanium dioxide (TiO2-x) was prepared by heating TiO2 in H-2 atmosphere, followed by the post-calcination in O-2 at different temperatures. The physicochemical properties of the products were characterized by X-ray photoelectron spectroscope (XPS), electron spin resonance (ESR), UV-Vis diffuse reflectance spectrum (UV-Vis DRS) and photoluminescence spectrum (PL). The photocatalytic activity of the as-prepared samples was determined by the degradation of gas-phase benzene under visible light (lambda > 400 nm) irradiation. The results show that the TiO2-x post-heated at 300 degrees C exhibits the highest photocatalytic activity. After photocatalytic oxidation for 4 h, the conversion rate of benzene over the catalyst is up to 36.9% at steady state, which is 5.3 times as much as that on the untreated sample. The enhanced photocatalytic performance of the TiO2-x is related to the amount of the oxygen vacancies in matrix (single-electron-trapped oxygen vacancies). The postcalcination successfully reduces the surface oxygen vacancies (Ti3+), efficiently hindering the photoinduced carriers from recombination.