稀土Sm掺杂TiO2第一性原理计算及光催化性能评价

First-principles calculation and photocatalytic property evaluation of rare earth Sm doped TiO2

以钛酸四丁酯和六水合硝酸钐为原材料,采用溶胶-凝胶法制备了纯二氧化钛(TiO2)及镧系稀土钐(Sm)掺杂改性TiO2光催化剂。基于密度泛函理论第一性原理,采用分子模拟对纯TiO2及Sm掺杂改性TiO2光催化剂的电子结构进行计算分析,并对样品进行表征。以卤素灯为可见光源,目标污染物为一氧化氮(NO)气体,评价了各样品在可见光条件下对NO气体的光催化活性。结果表明,Sm掺杂改性能调整TiO2晶体的内部电子结构,Sm^3+取代Ti^4+形成氧空位及晶格缺陷,引入中间杂质能级,抑制光生电子与空穴的有效复合,降低带隙宽度,提升光催化剂的光响应范围及光催化活性。在稀土Sm掺杂量为0.2%(质量分数),煅烧温度为550℃,光照时间为40min的条件下,Sm掺杂改性TiO2光催化剂对NO的降解率达到81.74%。

Pure titanium dioxide(TiO2)and Sm doped modified TiO2 photocatalyst samples were prepared by sol-gel method with titanate four butyl ester and six hydrate samarium nitrates as raw material.Based on the first principle of density functional theory,the electronic structures of pure phase and Sm-TiO2 were analyzed using molecular simulation,and the samples were characterized.Halogen lamp was used as the visible light source and nitric oxide(NO)was utilized as the pollution source,and the photocatalytic activity of the samples under visible light was evaluated.The results shown that Sm doped TiO2 can adjust the internal electronic structure of TiO2 crystal.Sm^3+substituted Ti^4+formation of oxygen vacancies and lattice defects so that intermediate impurity levels were introduced.The recombination of photogenerated electrons and electron hole were inhabited so that the width of the band gap was reduced which improved the light response range of photocatalyst and photocatalytic activity.The degradation rate of NO by Sm doping TiO2 reached 81.74%under the conditions of Sm doping content of 0.2%(mass fraction),calcination temperature of 550℃and illumination time of 40 minutes.