Physical and Photocatalytic Properties of CeO2/ZnO/ZnAl2O4 Ternary Nanocomposite Prepared by Co-precipitation Method

Abstract ZnAl2O4 spinel nanoparticles and CeO2/ZnO/ZnAl2O4 ternary nanocomposites were synthesized by a co-precipitation method. The structural, morphological, optical properties and chemical compositions of the products were analyzed respectively by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS) and X-ray fluorescence (XRF) spectroscopy. The optical band gap of ZnAl2O4 spinel nanoparticles was 3.220 eV. When 1.0 mmol Ce(NO3)3•6H2O was added to the synthesis reaction, the optical band gap of the obtained ternary nanocomposite was 3.170 eV. The influence of phase composition, optical band gap, oxygen vacancy and specific surface area on photocatalytic activity over CeO2/ZnO/ZnAl2O4 ternary nanocomposites was investigated. The CeO2/ZnO/ZnAl2O4 nanocomposite prepared with 1.0 mmol Ce(NO3)3•6H2O showed the lowest recombination rate of photoexcited electron-hole pairs, the narrowest optical band gap (3.170 eV) and the highest oxygen vacancy concentration or highest Urbatch energy (0.299 eV). These parameters produced the best photocatalytic activity toward methylene blue (MB) under UV irradiation. The CeO2/ZnO/ZnAl2O4 ternary nanocomposites exhibited better photocatalytic performance than pure ZnAl2O4 spinel nanoparticles and 100% degradation of aqueous MB solution was achieved within 60 min when using the CeO2/ZnO/ZnAl2O4 ternary nanocomposite photocatalyst synthesized with 1.0 mmol Ce(NO3)3•6H2O.

摘要：采用共沉淀法合成了ZnAl₂O₄尖晶石纳米颗粒与CeO₂/ZnO/ZnAl₂O₄三元纳米复合材料。分别通过X射线衍射（X-ray diffraction, XRD）、扫描电子显微镜（scanning electron microscopy, SEM）、漫反射光谱（diffuse reflectance spectroscopy, DRS）与X射线荧光（X-ray fluorescence, XRF）光谱分析了产物的结构、形貌、光学性能与化学组成。ZnAl₂O₄尖晶石纳米颗粒的光学带隙为3.220 eV。当合成反应体系中添加1.0 mmol硝酸铈(Ⅲ)六水合物（Ce(NO₃)₃·6H₂O）时，所得三元纳米复合材料的光学带隙为3.170 eV。本研究探讨了相组成、光学带隙、氧空位及比表面积对CeO₂/ZnO/ZnAl₂O₄三元纳米复合材料光催化活性的影响。以1.0 mmol硝酸铈(Ⅲ)六水合物制备的CeO₂/ZnO/ZnAl₂O₄纳米复合材料，其光生电子-空穴对复合率最低、光学带隙最窄（3.170 eV）且氧空位浓度最高或厄尔巴赫（Urbach）能量最高（0.299 eV）。上述参数赋予该材料在紫外光照下对亚甲基蓝（methylene blue, MB）最优的光催化活性。CeO₂/ZnO/ZnAl₂O₄三元纳米复合材料的光催化性能优于纯ZnAl₂O₄尖晶石纳米颗粒；采用该1.0 mmol硝酸铈(Ⅲ)六水合物合成的CeO₂/ZnO/ZnAl₂O₄三元纳米复合材料光催化剂，可在60分钟内实现水溶液中亚甲基蓝的100%降解。