Significant effect of iodide addition on water splitting into H2 and O2 over Pt-loaded TiO2 photocatalyst: suppression of backward reaction

Direct water splitting into H2 and O2 over Pt-loaded semiconductor photocatalysts such as Pt–TiO2 was investigated. We found that addition of a small amount of iodide anion, I−, into the aqueous suspension of Pt–TiO2–anatase photocatalyst significantly improved the splitting into H2 and O2 with a stoichiometric ratio. The iodide anion was adsorbed preferentially onto Pt co-catalyst as iodine atom, I. This iodine layer effectively suppressed the backward reaction of water formation from H2 and O2 to H2O over the Pt surface.