稀土Sm掺杂对纳米TiO_2结构和可见光催化性能的影响

Effect of Sm Doping on Structure and Visible Light Photocatalytic Properties of Nano-TiO_2

采用溶胶-凝胶法制备了纯TiO_2和稀土Sm掺杂TiO_2纳米粉体(Sm-TiO_2),通过XRD、XPS、FT-IR、UV-VisDRS、PL和Nano-sizer纳米粒度仪等对样品进行表征,以亚甲基蓝(MB)的光催化降解为探针反应,探讨稀土Sm掺杂对纳米TiO_2的结构和可见光催化性能的影响。结果表明,Sm掺入TiO_2后在表面存在Sm^(3+)和Sm2+两种价态,Sm掺杂抑制了TiO_2从锐钛矿向金红石的相转变,阻碍纳米晶粒生长,增加了纳米粉体表面羟基含量;适量的Sm掺杂能使TiO_2吸收光谱的阈值波长红移,有效降低光生e-/h+的复合率,提高TiO_2光催化活性。热处理温度500℃时,掺杂1.0wt%Sm的纳米TiO_2样品在普通日光灯下对MB在6 h内的光催化降解效率达97%,明显高于同等条件下Degussa公司产品P25的降解率56%。

The pure and Sm-doped TiO2 nanopowders were prepared by sol-gel method. The samples were characterized by XRD,XPS,FT-IR,UV-Vis,PL and Nano-sizer nano particle size analyzer,etc. The effects of Sm-doping on structure and visible photocatalytic properties of TiO2 photocatalyst was evaluated by photocatalytic degradation of methylene blue（MB） under the irradiation of fluorescent lamp. The results show that samarium appeared two kinds of Sm^3 ＋and Sm^2 ＋valence state on the surface of TiO2.Samarium doping can restrain the phase transfer from anatase to rutile,prevent the grain growth,and increase the surface hydroxyl content. Appropriate doping amount of Sm can broaden TiO2＇s,spectrum absorption region to visible light and effectively inhibit the recombination of photoelectron-hole pairs.Meanwhile,the photocatalytic activity of the 1. 0wt% Sm-doped TiO2 samples calcined at 500 ℃ is the better under the irradiation of fluorescent light,it is 97% within 6 h and significantly higher than 56% of P25 produced by Degussa under the same experimental conditions.