Ce-TiO_2复合粉体晶相控制与光催化性能研究

Study on Crystalline Controlling and Photocatalytic Activity of Ce-TiO_2 Compound Powders

为了系统研究Ce-TiO2的晶相形成规律及其对光催化性能的影响,本文采用Sol-gel法制备了Ce-TiO2复合粉体,使用XRD、XPS等手段分别对其结构和性能进行了分析表征,研究了Ce4+添加量、烧结温度、保温时间对样品晶相的影响,阐述了Ce-TiO2晶相的形成规律及机理,并进行了光催化降解实验.结果表明:Ce4+添加量在1%～16%之间时,样品为Ce掺杂型TiO2;Ce4+添加量在16%～48%之间时,样品为CeO2-TiO2复合体系;Ce4+添加量大于48%以后,TiO2成为无定型态.其中,锐钛矿相TiO2结晶所需的烧结温度在510～680℃之间;金红石相TiO2结晶所需的烧结温度在680℃以上.保温时间能改变晶型的完整度.在可见光激发下,当样品TiO2中锐钛矿相和金红石相的含量比例为3∶1时,对甲基橙降解率达到最高(79.7%).

In order to investigate the crystalline formation and its effects on the photocatalytic performance, Ce - TiO2 compound powders are prepared by Sol- gel method, and their crystal structure and improperties are then characertized by XRD and XPS measurements. The effects of the content of Ce4 ＋ , annealling temperature, and holding time on the crystal phase are also analyzed. The law and mechanism of crystalline formation of Ce - TiO2 compound powders are elaborated thereafter. The methyl orange degradation rate of sample in different crystalline ratio are finally tested. It is suggested through the results that： when the content of Ce4＋ is in the range of 1% 16% , the sample is Ce -doped TiO2; when the content of Ce4＋ is in the range of 16% -48% , the sample is CeO2 -TiO2 compound system; when the content of Ce4＋ is larger than 48% , the TiO2 is amorph strucure. In the compound powders, anatase phase is formed in the annealing temperature range of 510 -680℃; and rutile phase is formed in the annealing temperature over 680℃. Holding time can improve lattice integrity. In the com- pound powders, if the phase content ratio between anatase and rutile is 3 ： 1, the degradation rate of methyl or- ange reaches the highest （79.7%） under visible-light irradiation.