Isotope tracing study on oxidation of water on photoirradiated TiO2 particles

Water is oxidized to molecular oxygen on a TiO2 photocatalyst using electron acceptors such as Ag+ and Fe3+ ions. However, there has been no information about whether this reaction occurs or not using molecular oxygen as the electron acceptor. We found by analysis of oxygen in the gas phase using 18O-enriched water that this reaction does in fact occur. The quantum efficiency was higher with rutile-form particles than with anatase-form particles. O2 was photocatalytically produced using O atoms supplied solely from water even in the presence of O2 in the system. These results are important for deepening the understanding of TiO2 photocatalysts because molecular oxygen is used most frequently as the electron acceptor and the intermediates of oxidation of water are involved in various kinds of photocatalytic reactions.

Figure optionsDownload as PowerPoint slideHighlights▸ Water is oxidized on TiO2 photocatalysts using O2 as the electron acceptor. ▸ As a result, O2 is produced using O atoms supplied solely from water. ▸ Rutile particles showed 3-times higher quantum efficiencies than anatase particles. ▸ Larger particles showed higher efficiency for both rutile and anatase particles.