TiO_(2-y)N_x纳米光催化剂的制备及其可见光响应机理  

Preparation and Visible-light Responsive Mechanism of Nanoscale TiO_(2-y)N_x Photocatalyst

作　　者：王城英[1] 姜洪泉[1] 李井申[1] 卢智宇[1] 闫盼盼[1] 

机构地区：[1]哈尔滨师范大学化学化工学院,哈尔滨150500

出　　处：《应用化学》2010年第12期1413-1418,共6页Chinese Journal of Applied Chemistry

基　　金：黑龙江省教育厅科学技术研究项目(11551115);哈尔滨师范大学青年学术骨干资助计划项目(08XBSK89)

摘　　要：利用溶胶-凝胶技术,以尿素为氮源,采用原位掺杂方式制备了TiO2-yNx纳米粉体;以亚甲基蓝(MB)溶液在可见光下的光催化降解评价其可见光催化活性;考察了体系初始pH值、N的掺杂量和焙烧温度对样品可见光催化活性的影响。结合XRD、XPS、ESR和DRS测试技术,研究了N掺杂纳米TiO2的可见光响应机理。研究结果表明,TiO2-yNx纳米粉体的优化制备工艺条件为:体系初始pH=0.52,掺杂比n(N)∶n(Ti)=1∶6,焙烧温度为440℃。此条件下制备的样品N含量为0.77%,为单一的锐钛矿相,平均粒径为19.0nm,具有良好的可见光催化活性。N掺杂导致TiO2纳米粉体的表面羟基含量增加,形成了大量束缚单电子的氧空位;N取代晶格O形成了N—Ti—O和O—N—Ti键合结构。N掺杂导致TiO2纳米粒子的吸收带边红移,对可见光的吸收能力明显增强,这表明N掺杂改变TiO2电子结构,使带隙窄化,降低光响应阈值。N掺杂TiO2纳米粒子的可见光响应归因于N取代掺杂形成的掺杂能级与氧空位形成的缺陷能级共同作用所致。TiO2-yNx nanoparticles were prepared by in situ doping sol-gel method using urea as the nitrogen source.Their visible-light photocatalytic activity was evaluated by the photocatalytic degradation of methylene blue（MB） in an aqueous solution under visible-light irradiation.The effects of original pH value,nitrogen-doping content and calcination temperature on the as-prepared samples were investigated.The visible-light responsive mechanism of the N-doped sample was studied by means of XRD,XPS,ESR and DRS.The results show that the optimal conditions for the preparation of TiO2-y Nx nano-particles are as follows：original pH value 0.52,doping proportion of n（N） to n（Ti） 1：6,and calcination temperature 440 ℃.The as-prepared sample of single anatase phase with 0.77% N atoms and with average crystal size 19.0 nm exhibits a good visible-light photocatalytic activity.N-doping leads to increasing the surface hydroxyl groups and forming abundant surface oxygen vacancies bounding single-electrons.The O atoms in the TiO2 lattice are substituted by the doped N atoms so that form the N—Ti—O and O—N—Ti bonding structures.N-doping results in a remarkable red-shift of the TiO2 absorption band-edge and significantly increases the absorption of visible-light.The results indicate that N-doping changes the electronic structure of TiO2 and decreases the band-gap.The visible-light response of the N-doped sample is ascribed to a synergetic effect of impurity and defect energy levels that are originated from the substitutional N-doping and the formation of oxygen vacancies accordingly.

关 键 词：纳米TIO2 氮掺杂 溶胶-凝胶 可见光响应 光催化 

分 类 号：O614.4[理学—无机化学] O643.3[理学—化学]