CeO2 nanoscale particles:Synthesis,characterization and photocatalytic activity under UVA light irradiation
来源期刊：JOURNAL OF RARE EARTHS2018年第6期
论文作者：Laouedj Nadjia Elaziouti Abdelkader Benhadria Naceur Bekka Ahmed
文章页码：575 - 587
摘 要：CeO2 nanoparticles（NPs） were synthesized in alkaline medium via the homogeneous precipitation method and were subsequently calcined at 80 ℃/24 h（assigned as CeO2-80） and 500 ℃/2 h（assigned as CeO2-500）. The as-prepared materials and the commercial ceria（assigned as CeO2-com） were characterized using TGA-MS, XRD, SEM-EDX, UV-vis DRS and IEP techniques. The photocatalytic performances of all obtained photocatalysts were assessed by the degradation of Congo red azo-dye（CR） under UVAlight irradiation at various environmental key factors（e.g., reaction time and calcination temperature）.Results reveal that CeO2 compounds crystalize with cubic phase, CeO2-500 exhibits smaller crystallite size（9 nm vs 117 nm） than that of bare CeO2-com. SEM analysis shows that the materials are sphericallike in shape NPs with strong assembly of CeO2 NPs observed in the CeO2-500 NPs. EDX analysis confirms the stoichiometry of CeO2 NPs. UV-vis DRS measurement reveals that, CeO2-500 NPs exhibits a red-shift of absorption band and a more narrow bandgap（2.6 eV vs 3.20 eV） than that of bare CeO2-com. On the contrary, Urbach energy of Eu is found to be increased from 0.12 eV（CeO2-com） to 0.17 eV（CeO2-500）,highlighting an increase of crystalline size and internal microstrain in the CeO2-500 NPs sample. Zeta potential（IEP） of CeO2-500 NPs is found to be 7.2. UVA-light-responsive photocatalytic activity is observed with CeO2-500 NPs at a rate constant of 10×10-3 min-1, which is four times higher than that of CeO2-com(Kapp=2.4×10-3 min-1) for the degradation of CR. Pseudo-first-order kinetic model gives the best fit. On the basis of the energy band diagram positions, the enhanced photocatalytic performance of CeO2-500 nano-catalyst can be ascribed to O2-, ’OH and R’+ as the primary oxidative species involved in the degradation of RC under UVA-light irradiation.
Laouedj Nadjia1，Elaziouti Abdelkader2，Benhadria Naceur1，Bekka Ahmed1
1. Laboratory of Inorganic Materials and Application L.I.M.A,University of Science and Technology Oran Mohammed Boudiaf (USTO M.B)2. Laboratory of Electron Microscopy and Materials Science L.E.M.M.S,University of Science and Technology Oran Mohammed Boudiaf (USTO M.B)
摘 要：CeO2 nanoparticles（NPs） were synthesized in alkaline medium via the homogeneous precipitation method and were subsequently calcined at 80 ℃/24 h（assigned as CeO2-80） and 500 ℃/2 h（assigned as CeO2-500）. The as-prepared materials and the commercial ceria（assigned as CeO2-com） were characterized using TGA-MS, XRD, SEM-EDX, UV-vis DRS and IEP techniques. The photocatalytic performances of all obtained photocatalysts were assessed by the degradation of Congo red azo-dye（CR） under UVAlight irradiation at various environmental key factors（e.g., reaction time and calcination temperature）.Results reveal that CeO2 compounds crystalize with cubic phase, CeO2-500 exhibits smaller crystallite size（9 nm vs 117 nm） than that of bare CeO2-com. SEM analysis shows that the materials are sphericallike in shape NPs with strong assembly of CeO2 NPs observed in the CeO2-500 NPs. EDX analysis confirms the stoichiometry of CeO2 NPs. UV-vis DRS measurement reveals that, CeO2-500 NPs exhibits a red-shift of absorption band and a more narrow bandgap（2.6 eV vs 3.20 eV） than that of bare CeO2-com. On the contrary, Urbach energy of Eu is found to be increased from 0.12 eV（CeO2-com） to 0.17 eV（CeO2-500）,highlighting an increase of crystalline size and internal microstrain in the CeO2-500 NPs sample. Zeta potential（IEP） of CeO2-500 NPs is found to be 7.2. UVA-light-responsive photocatalytic activity is observed with CeO2-500 NPs at a rate constant of 10×10-3 min-1, which is four times higher than that of CeO2-com(Kapp=2.4×10-3 min-1) for the degradation of CR. Pseudo-first-order kinetic model gives the best fit. On the basis of the energy band diagram positions, the enhanced photocatalytic performance of CeO2-500 nano-catalyst can be ascribed to O2-, ’OH and R’+ as the primary oxidative species involved in the degradation of RC under UVA-light irradiation.
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