TITANIUM-DIOXIDE PHOTOSENSITIZED REACTIONS STUDIED BY DIFFUSE REFLECTANCE FLASH-PHOTOLYSIS IN AQUEOUS SUSPENSIONS OF TIO2 POWDER

Diffuse reflectance and transmission flash photolysis have been used to study the primary reaction intermediates in titanium dioxide (TiO2) photosensitized reactions of potassium iodide, 2,4,5-trichlorophenol, methyl viologen dichloride, potassium tetrachloroplatinum(II), tris(1,10-phenanthroline)-iron(II) perchlorate, N, N, N', N'tetramethyl-p-phenylenediamine, and thianthrene. In the cases where the product of OH radical mediated oxidation is different from that of direct electron transfer oxidation, only products of direct electron transfer oxidation are observed. The products of direct electron transfer and OH radical mediated oxidation of iodide and tetrachloroplatinum are identical. The transient decay kinetics in TiO2 powder systems appear to be first order with a Gaussian distribution of reaction rate constants reflecting the distribution of particle radii. © 1990, American Chemical Society. All rights reserved.