稀土修饰TiO2光催化降解甲基橙反应机理

采用溶胶-凝胶法制备纯的及掺杂不同量Ce的TiO2纳米粒子,利用UV-Vis漫反射光谱及XRD等对所制备样品进行表征,以紫外灯为光源,甲基橙水溶液的脱色为模型反应,研究了CeO2/TiO2的光催化降解反应活性.实验发现:掺杂Ce的TiO2纳米粒子反射光谱特性向可见光方向红移到了500nm;掺杂Ce的TiO2纳米粒子比纯的TiO2纳米粒子对光的吸收率高、吸收能力强;掺杂的Ce4+仅有少量进入TiO2晶格中,而大部分的Ce4+没有进入TiO2晶格中,而是以小团簇的CeO2形态均匀地分散在TiO2纳米粒子中或者是覆盖在其表面上,说明了掺杂Ce能提高TiO2光催化反应活性,且掺杂Ce最佳浓度是2.0mol%.光催化降解反应机理可能有两种途径,一种途径是掺杂离子协同光催化降解甲基橙反应机理,另一种途径是光敏剂与掺杂离子协同光催化降解甲基橙反应机理.

Photocatalytic degradation mechanism of methyl orange by rare-earth doped TiO2

Pure nano-TiO 2 particles and those doped with various contents of Ce were prepared by sol-gel process and characterized by UV-Vis and XRD spectra.Being a model reaction,the photocatalytic degradation of methyl orange in aqueous solution in the presence of CeO2/TiO2 nano-particles was investigated.Results show that the reflective spectral characteristic of rare-earth Ce doped nano-TiO2 particles is moved to the visible region with a red shift to 500 nm,and the absorption of visible and UV light of rare-earth Ce doped nano-TiO2 is enhanced.It is indicated that a few Ce 4+ doped enters into the crystal lattices of TiO2,a lot of Ce 4+ doped are uniformly dispersed into TiO2 or covered onto TiO2 as the form of CeO2 with small size,which explains that the rare-earth Ce doping enhances the photocatalytic activity of TiO2,and the optimum content of CeO2 in CeO2/TiO2 is 2.0 mol%.Photodegradation mechanism of methyl orange has probably two kinds of ways.One is the degradation mechanism of methyl orange in photocatalysis enhanced by doped ion,the other is that enhanced by doped ion and photosensitized reagent.