Semiconductor-catalyzed solar photooxidation of iodide ion

With natural sunlight TiO2 (anatase), ZrO2, MoO3, Fe2O3, ZnO, CeO2 and Al2O3 microparticles photocatalyze the oxidation of iodide ion but CuO, ZnS, CdO, CdS, HgO, PbO, Sb2O3 and Bi2O3 microparticles do not. The photocatalysis is not slowed down at least up to 120 min with ZrO2, MoO3, Fe2O3, CeO2 and Al2O3 whereas it is 45 min with TiO2 and 30 min with ZnO. The iodine generation depends on [I−], surface area and pH and is enhanced by the addition of ethanol. The catalysts show sustainable photocatalysis. Nanoparticles exhibit higher photocatalytic activities than microparticles. The catalytic efficiencies are of the order: Fe2O3 > MoO3 > TiO2 > CeO2 > ZnO > ZrO2 > Al2O3.

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