Gadolinia-modified ceria photocatalyst for removal of lead (II) ions from aqueous solutions

Gd2O3-modified CeO2 particles are prepared by a solid-state reaction method, and are used to remove Pb(II) ions from aqueous solutions by a photoelectrodeposition. The UV–photocatalytic activity for Pb(II) ion removal of the Gd2O3-modified CeO2 is significantly higher than that of pure CeO2. A solid solution Gd0.1Ce0.9O1.95 phase coexisting with the CeO2 matrix phase shows a high ability of photoelectrodeposition for the Pb(II) ions removal, compared to the two-phases mixture of Gd2O3–CeO2. The high photocatalytic activity is also supported by a strong photoluminescence (PL) signal from the Gd0.1Ce0.9O1.95–CeO2. The high activity can be due to a formation of heterojunctions between p-type Gd0.1Ce0.9O1.95 and n-type CeO2, promoting transfer of photogenerated electron–hole pairs and efficiency restraining recombination of the charges.