Correlation between photoreactivity and photophysics of sulfated TiO 2 photocatalyst

Abstract

The sulfated TiO 2 were prepared by dipping TiO 2 in H 2SO 4 solutions. The reactivity of methylene blue photocatalytic degradation of all SO 4 2−/TiO 2 are higher than that of TiO 2, and the optimum molar concentration of SO 4 2− on TiO 2 is 9%. IR confirmed that the chelating bidentate SO 4 2− and unidentate SO 4 2− coexist in SO 4 2−/TiO 2. Methylene blue is cationic dye. Maybe the Lewis acid and Bronsted acid coexist in the SO 4 2−/TiO 2 catalyst, the adsorption of methylene blue on the catalyst increases. The high photocatalytic reactivity of SO 4 2−/TiO 2 is consistent with the good adsorption. The presence of SO 4 2− enhances the light absorption in the visible region of SO 4 2−/TiO 2, and the photocatalytic activity of SO 4 2−/TiO 2 correlates with reflectance of the samples in the visible light region. The fluorescence spectra show that weaker the fluorescence intensity the higher the activity. Thus, The enhanced photocatalytic activity of SO 4 2−/TiO 2 may be explained by the good adsorption of methylene blue on the catalysts, high light absorption in the visible region, and weak fluorescence intensity.