摘要
采用溶胶凝胶法合成了一系列Ce掺杂ZnO粉晶。采用XRD, UV-VIS, FT-IR, PL技术及以亚甲基蓝溶液脱色反应为模型,研究了Ce掺杂ZnO晶体结构、光学带隙、成键、光致发光及光催化性能产生的不同机理。结果表明:低含量Ce掺杂和高含量Ce掺杂对ZnO结构和性能产生的机理存在差异。低含量Ce掺杂时,ZnO晶格参数及Zn-O键长因原子半径大的Ce~(3+)替代原子半径小的Zn~(2+)而增加,光学带隙因Burstein-Moss效应而宽化,结晶性能因ZnO成核空间增加而提高,青蓝色发光峰因结晶性能提高而减弱。高含量Ce掺杂时,ZnO晶格参数及Zn-O键长因Ce~(3+)Ce~(4+)转化而减小,光学带隙因Ce~(3+)占据Zn~(2+)格位而减小,结晶性能因氧化铈包覆作用并降低结晶速率而提高,青蓝色发光峰随缺陷增加而增强。Ce掺杂ZnO光催化能力随光学带隙减小而提高。光催化性能最优Ce掺杂量为2%。FT-IR表明系列Ce掺杂ZnO均含有Zn-O和Ce-O-Zn等成键。
A series of Ce doped ZnO powders were synthesized by sol-gel method. The crystal structure, optical band gap, bonding, photoluminescence and photocatalytic properties of Ce-doped ZnO were studied by XRD, UVVIS, FT-IR, PL technology and based on the decolorization reaction of methylene blue solution. The results show that the mechanism of low and high Ce doping on the structure and properties of ZnO is different. When Ce content is low, the lattice parameters and bond length of ZnO increase because Ce~(3+)with larger atomic radius replaces Zn~(2+) with smaller atomic radius. The optical band gap is broadened because of Burstein-Moss effect. The crystallinity is improved because of the increase of nucleation space of ZnO, and the blue emission peak is weakened because of the improvement of crystallinity. When Ce content is high, the lattice parameters of ZnO and the bond length of ZnO decrease due to the conversion of Ce~(3+)Ce~(4+), the optical band gap decreases because Ce~(3+)occupies the lattice position of Zn~(2+), the crystallinity increases due to the encapsulation of CeO_2 and the reduction of crystallization rate,and the blue emission peak increases with the increase of defects. The photocatal ytic activity of Ce-doped ZnO increases with the decrease of optical bandgap. And the optimum Ce doping content for photocatalytic performance is2%. At the same time, FT-IR showed that all Ce-doped ZnO contained Zn-O and Ce-O-Zn bonds.
引文
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