Optical properties and reactions of radiation induced TiO2 electrons in aqueous colloid solutions

This work involves an experimental study of the optical properties of excess electrons in solvated TiO2 nanoparticles. The excess electrons were produced by irradiation of deaerated 2-propanol solutions containing TiO2 nanoparticles in acidic pH, The irradiation produced propanol radicals and hydrated electrons, which react with TiO2 sols and produce the blue color of excess TiO2 electrons. Results are provided for the maximum loading of electrons on the TiO2 nanoparticles for both Q-particles and large nanocrystallites, and for the extinction coefficients, which were determined by titration. Discussion of the gamma electron spectra in the light of earlier work is presented. In addition, we find that the high local concentration of electrons enables reduction of H2O2 and ClO4- by simultaneous two-electron transfer.