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用混合溶胶 凝胶法制备了Fe3+,Zn2 +,Pd ,Co2 +,Ni2 +,Cr3+等金属离子掺杂的二氧化钛复合微粒。以四环素降解为目标反应 ,研究了所制备的复合微粒光催化活性与选择性。并用IR、XPS、Raman光谱等技术 ,探讨了影响复合微粒光催化活性的原因。结果显示 :掺杂Fe3+、Zn2 +的二氧化钛复合微粒对四环素降解具有很高的催化活性与选择性 ;掺杂Pd的复合微粒催化活性也有所提高。而Co2 +,Ni2 +,Cr3+等金属离子掺杂的二氧化钛复合微粒的催化活性呈下降趋势。研究认为 :Fe3+、Zn2 +促进二氧化钛微粒光催化活性的原因是由于这些金属离子高度分散在二氧化钛基质中 ,使基质晶型发生畸变并形成Ti O M桥氧结构 ;这种结构使复合微粒表面缺陷和活性比表面积增加 ,有利于光生载流子的转移。同时 ,Ti/Fe复合微粒中Fe3+有利于活性·OH基团的形成。这些活性·OH基团插入有机物的C H键中 ,最终导致有机物的完全降解矿化。另一方面 ,由于Fe3+,Zn2 +,Pd特殊的电子构型 ,有利于浅度捕获半导体的光生电子 ,使光生电子 空穴对有效分离。而Co2 +,Ni2 +,Cr3+金属离子的电子构型易深度捕获光生电子 ,结果可能形成了电子 空穴复合中心 ;导致半导体的量子效率和催化活性下降
Titania composite particles doped with metal ions such as Fe3 +, Zn2 +, Pd, Co2 +, Ni2 + and Cr3 + were prepared by sol-gel method. Taking tetracycline degradation as the target reaction, the photocatalytic activity and selectivity of the prepared composite particles were studied. The reasons that affect the photocatalytic activity of the composite particles were discussed by IR, XPS and Raman spectroscopy. The results showed that the composite particles doped with Fe3 + and Zn2 + have high catalytic activity and selectivity for the degradation of tetracycline. The catalytic activity of the composite particles doped with Pd is also improved. However, the catalytic activity of TiO2 / TiO2 doped with metal ions such as Co2 +, Ni2 + and Cr3 + showed a decreasing trend. It is concluded that the reason why Fe3 +, Zn2 + promote the photocatalytic activity of TiO2 particles is because these metal ions are highly dispersed in the TiO2 matrix, distorting the matrix crystal structure and forming Ti OM bridging oxygen structure. This structure makes the surface defects of composite particles and Active surface area increases, is conducive to the transfer of photo-generated carriers. Meanwhile, Fe3 + in the Ti / Fe composite particles favors the formation of active · OH groups. These active · OH groups are inserted into the C H bonds of the organics, eventually leading to complete degradation of the organics. On the other hand, due to the special electronic configuration of Fe3 +, Zn2 + and Pd, it is advantageous to capture the photogenerated electrons of the semiconductor shallowly and effectively separate the photogenerated electron-hole pairs. The electronic configuration of Co2 +, Ni2 + and Cr3 + metal ions easily captures photogenerated electrons, resulting in the formation of an electron-hole recombination center; resulting in the decrease of the quantum efficiency and the catalytic activity of the semiconductor