INCREASING THE EFFICIENCY OF THE PHOTOCATALYTIC OXIDATION OF ORGANIC FILMS ON AQUEOUS-SOLUTIONS BY REACTIVELY COATING THE TIO2 PHOTOCATALYST WITH A CHLORINATED SILICONE

In order to reduce the fraction of water and salt accessible surface O H sites on TiO2, the photocatalytic crystallites were reacted, in an H Cl-releasing reaction, with a chlorine-terminated chlorinated poly(dim ethylsiloxane) telomer, Glassclad 6C. When the overcoated photocatalys t was applied in the oxidation of organic films on aqueous 0.5 M NaCl, the number of O-2 molecules consumed per photon drastically increased . In the oxidation of n-octanal films, 1-25 molecules of O-2 were cons umed (five electrons were transferred to oxygen), and in the oxidation of n-octanoic acid, 0.15 molecules of O-2 were consumed (0.6 electron s was transferred) per photon. The overcoating reduced the O-2-consume d/CO2-produced ratio in the initial reaction period when most of the r eactant was intact. The enhancement of Oz uptake per photon and the pr oduction of oxidized organic compounds, instead of CO2, are attributed to chloride ion exclusion from the reaction zone and to fast hole oxi dation, producing a radical, followed by prompt electron injection by the radical, resulting in two-electron oxidation.