Mechanism of Photocatalytic Production of Active Oxygens on Highly Crystalline TiO_2 Particles by Means of Chemiluminescent Probing and ESR Spectroscopy

摘要

The effect f calcination on photocatalytic activities was studied for highly crystalline TiO_2 Powder ,which was synthesized by the method of hydrothermal crystallization in organic media(HyCOM).The productions of O_2~(centre -) and H_2O_2 under ambient condition were monitored by means of luminol chemiluminescence probing .The amount of produced O_2~(centre -) was decreased with calcination at lower temperatures in parallel to the decrease of Ti~(3+) signal observed at 77 K by ESR spectroscopy,The formation route for H_2O_2 under aerated condition is mainly two-step O_2 reduction in the presence of oxidizable organic molecules such as luminol.Oxidization activity was significantly high when HyCOM-TiO_2 was calcined at higher temperatures ,973-1173 K, as monitored by the luminol is oxidized via hydroxyl radical rather than the direct oxidation by photoinduced surface trapped holes.