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

Gd 2 O 3 -modified CeO 2 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 Gd 2 O 3 -modified CeO 2 is significantly higher than that of pure CeO 2 . A solid solution Gd 0.1 Ce 0.9 O 1.95 phase coexisting with the CeO 2 matrix phase shows a high ability of photoelectrodeposition for the Pb(II) ions removal, compared to the two-phases mixture of Gd 2 O 3 –CeO 2 . The high photocatalytic activity is also supported by a strong photoluminescence (PL) signal from the Gd 0.1 Ce 0.9 O 1.95 –CeO 2 . The high activity can be due to a formation of heterojunctions between p-type Gd 0.1 Ce 0.9 O 1.95 and n-type CeO 2 , promoting transfer of photogenerated electron–hole pairs and efficiency restraining recombination of the charges. [ABSTRACT FROM AUTHOR]