Publication costs assisted by the Centre National de la Recherche Sclentifique Oxygen isotopic exchange (OIE) measurements have been carried out over UV irradiated anatase samples. At room temperature, simultaneous action of Ti02 and UV light is needed for OIE which proceeds via a mechanism involving one oxygen surface atom at a time. For various anatase samples, the photocatalytic activities per unit of catalyst area for OIE and for isobutane oxidation (IOX) into acetone correlate. UV irradiation of a mixture of í-C4H10 and of an excess of 1802 shows that OIE occurs only after IOX. It is inferred that the same dissociated surface oxygen species participate in both reactions.

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A synthesis of studies on the photocatalytic oxidation of various compounds (isobutane, propene, alkyltoluenes, butanols, ammonia, halide ions in aqueous solution) is presented, TiO2 being the main photocatalyst. Comparisons are also made with other n‐type semiconductors: ZrO2, V2O5, Sb2O4, ZnO, SnO2, CeO2, WO3. Information about the mechanism has been obtained by (i) an examination of the photocatalytic isotopic exchange of oxygen in competition with the oxidation of a hydrocarbon, (ii) kinetics and photoconductivity measurements, and (iii) oxidation of butanols by NO. The main conclusions are that these reactions proceed in an adsorbed phase and that dissociated oxygen species play an essential role.

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