TiO 2 corrosion during water photocleavage using Rh/TiO 2 suspensions

The absence of O2 evolution during water photocleavage experiments using basic aqueous suspensions of Rh/TiO2 photocatalysts, even after long irradiation periods (ca. 60 h), as well as the capacity of these catalysts to photo-adsorb O2, have been examined in terms of formation of peroxo species which remain at the TiO2 support thus leading to its progressive corrosion giving a thick layer of a titanium hydroxyperoxo-like compound. The role of this oxidized layer in the progressive decay observed in the rate of H2 photoproduction as well as the possibility of regeneration of the original photoactivity by bubbling an inert gas through the suspensions are examined.