Study of the Photocatalytic Performance of Oxygen-deficient TiO_2 Active in Visible Light

Oxygen-deficient titanium dioxide(TiO2-x)was prepared by heating TiO2 in H2 atmosphere,followed by the post-calcination in O2 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(λ400 nm)irradiation.The results show that the TiO2-x post-heated at 300℃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(Ti 3+),efficiently hindering the photoinduced carriers from recombination.