The photoproduction of O2 from a suspension containing CeO2 and Ce4+ cations as an electron acceptor

Herein we report the first finding on the photocatalytic production of oxygen from the irradiation of a CeO2-H2O-Ce-aq(4+) aqueous suspension. The O-2 yield strongly depended on the duration of irradiation, CeO2 concentration, concentration of Ce-aq(4+) cations, and pH of the suspension. The optimum photoproduction for O-2 was obtained under the following operating conditions: Illumination time > 15 h, CeO2 concentration: 2.5-5 g dm(-3), [Ce4+]: 4-5 mM, pH < 2, and illumination wavelength < 450 nm. The studied system utilizes CeO2 to accomplish the initial light absorption, charge separation, and O-2 evolution from the interaction of H2O molecules with holes in the CeO2 valence band, in the presence of Ce-aq(4+) species as an acceptor of conduction band electrons.