Photocatalytic Splitting of Liquid Water by n-TiO2 Suspension

By illumination (λ>300 nm) of a suspension of n-TiO2 (grain size ≦0.06 mm, 3 to 15 mg/ml) in aqueous acid solutions, containing 10-3 mol · dm-3 Ce4+ -ions an enhanced evolution of oxygen is observed. Its yield is dependent on the amount of TiO2 in the suspension and on the temperature. Using n-TiO2 suspended in diluted sulfuric acid, hydrogen and oxygen were produced in a ratio of about 2: 1. In both systems n-TiO2 is acting as an efficient electron donor. For the explanation of the processes probable reaction mechanisms are proposed.