Design and Synthesis of Sm, Y, La and Nd-doped CeO2 with a broom-like hierarchical structure: a photocatalyst with enhanced oxidation performance

CeO2 doped with various rare earth (RE) ions (Sm, Y, La and Nd) having a broom-like hierarchical structure was successfully prepared by a template-free hydrothermal method. The photooxidation performance of RE-doped products was significantly better than that of pure CeO2, and comparative experiments showed that Sm-doped CeO2 (SC) has superior photooxidation activity, resulting about 3.0-times and 8.5-times higher activities of bisphenol A (BPA) degradation and of acetaldehyde (CH3CHO) decomposition, respectively, than those of pure CeO2. Due to the incorporation of RE ions, the surface exposed cerium ions are partly substituted by those cations, resulting in a higher concentration of oxygen vacancies (O-v) in RE-doped CeO2. The increased O-v can act as a trapping center for photo-generated electrons to form a doping transition state between the conduction band (CB) and valence band (VB), which can restrict the recombination rate of electrons and holes effectively and lead to an outstanding enhancement of photooxidation performance. Furthermore, abundant highly reactive hydroxyl radicals ((OH)-O-.) and superoxide radicals (O-.(2)-), which are efficient intermediates with vivid oxidation ability, can further enhance the photocatalytic activity of RE-doped CeO2. A cost-effective strategy for designing CeO2-based semiconductor photocatalysts doped with multitudinous RE ions that have enhanced photooxidation performance is presented in this paper.