Photooxidation of iodide ion on immobilized semiconductor powders

MoO3 particles immobilized on an organic polymer, fixed on a glass plate, effectively catalyze the oxidation of iodide ion in air-saturated solution under illumination at 365 nm; the catalytic efficiency is higher than that of ZnO and anatase TiO2. Immobilized ZrO2, Fe2O3, Al2O3, Bi2O3, Y2O3, CeO2 and Nd2O3 particles also photocatalyze the oxidation. Except ZnO, all the listed metal oxides show sustainable photocatalytic activity at least up to 2 h; ZnO photocatalysis slackens after half-an-hour. Immobilized particulate CuO, ZnS, CdO, CdS, PbO and Sb2O3 fail to catalyze the photooxidation of iodide ion whereas SnO2 oxidizes iodide ion in dark itself; V2O5 dissolves. All the stated photocatalysis depend linearly on iodide ion concentration and enhance with the photon flux. The mechanistic detail of the photocatalysis is presented.