Photocatalytic oxidation of nitrogen monoxide over titanium(IV) oxide nanocrystals large size areas

The titania prepared by high-temperature hydrolysis of titanium alkoxides in a hydrocarbon solvent is highly active for the photocatalytic oxidation of NO to NO(2) and NO(3), The photocatalytic oxidation activity decreases with an increase in post-calcination temperature of the titania. The surface area and crystal size of the titania make some contributions to the photocatalytic oxidation activity. IR spectra show that ultraviolet (UV) irradiation of the titania promotes the formation of nitrate species. The data of ESR and IR lead to the conclusions that NO, when irradiating the titania with UV rays, reacts with O(2)(-) to form NO(2) and NO(3)(-), but the radicals generated as a result of secondary products of O(-) make no contribution to the photocatalytic oxidation. Tn addition, the concentration of free electron and O(2)(-) decreases significantly with an increase in post-calcination temperature of the titania. (C) 2000 Elsevier Science S.A. All rights reserved.