Homogenously Rare-Earth-Ion-Doped Nanoceria Synthesis in KOH-NaOH Molten Flux: Characterization and Photocatalytic Property

Homogeneously rare-earth (RE=La, Sm and Y) ions doped CeO2 nanoparticles (NPs) with enhanced photocatalytic performance were synthesized by a facile KOH-NaOH molten flux method. XRD, TEM, EDS mapping and XPS results demonstrate that RE cations have been successfully doped into the CeO2 lattice, which leads to the lattice expansion/shrinking, and more oxygen vacancies are generated after RE ions doping. The UV-Vis DRS and PL spectra indicate that RE-doped CeO2 samples have slightly narrower band gaps and significantly reduced photo-generated electron-hole recombination rates. 5% RE ions doped CeO2 NPs show excellent photocatalytic performances and the photodegradation ratio of methylene blue (MB) increases from 71.63% of undoped CeO2 to 76.35%, 77.51% and 77.37% for 5%-La, 5%-Sm and 5%-Y-doped CeO2 NPs, respectively. The obviously reduced recombination rate of e−/h+ pairs after RE ions doping may be the critical factor for the enhanced photocatalytic performance.