A relation between the non-stoichiometry and hydroxyl radical generated at photocatalytic TiO2 on 4CP decomposition

In order to know an interrelationship between OH radical generated on the TiO2 surface under an UV irradiation and the existence of non-stoichiometric titanium oxide of TiOx (0<x<2) in the TiO2, SIMS measurements and peak analyses of XPS on three kinds of TiO2 samples were carried out, and ESR spectra of DMPO-OH adduct through spin-trapping of OH radical generated on the TiO2 samples were measured. The generation of OH radical was approximately linear to the degree of non-stoichiometry of the TiO2. Removal of TOC of 4CP was affected by the total surface area of the particles in the TiO2 slurry and the non-stoichiometry within TiO2. The particle size in the slurry depended on the mixing condition of the preparation of the slurry and the morphology of agglomeration of TiO2 particles. The TiO2 particles in the slurry were dispersed in much smaller size than those of TiO2 samples on SEM.