Photosynthetic production of H2O2 from water at n-TiO2 electrodes in a photoelectrochemical cell: influence of electrolyte pH AND Pt electrodeposition

Abstract The electroreduction of photogenerated and/or dissolved oxygen to H 2 O 2 at n-TiO 2 polycrystalline electrodes in a photoelectrochemical cell has been studied by means of photocurrent transients and the rotating ring-disk electrode technique. The photoproduction of H 2 O 2 from water under open circuit (photocatalytic mode), in a basic medium, reaches an efficiency η (defined as the ratio between the generation rates of H 2 O 2 and “effective” h + + - e − pairs) of ~1%. By contrast, under external polarization (photoelectrochemical mode) η reaches maximum values of about 10%. This value decreases drastically at acidic pHs because of the high overpotential for O 2 electroreduction at n-TiO 2 . The effect of Pt overlayers on η has also been analysed.