Bi、S共掺杂对TiO_2纳米颗粒的结构和光催化性能的影响

Effects of Codoped Bi and S on the Textural Properties and Photocatalytic Activity of TiO_2 Nanoparticles

以钛酸丁酯、硝酸铋和硫脲为原料,采用溶胶-凝胶法制备了不同n[Bi(S)]/n(Ti)的Bi、S共掺杂的TiO2光催化剂。采用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、激光拉曼光谱(FT-Raman)、紫外-可见漫反射吸收光谱(UV/vis DRS)、微反等方法对光催化材料进行了研究。结果显示,Bi、S元素在TiO2纳米颗粒中分别以Bi2O3和SO42-形式存在,共掺杂未能改变TiO2的锐钛矿结构。Bi掺杂后,通过形成Bi—O—Ti键在TiO2禁带中产生了杂质能级,降低了纳米材料的禁带宽度,从而提高了光吸收效率;而S的引入,增多了催化剂表面的酸性位,有利于光催化活性的提高。Bi、S掺杂能明显改善TiO2纳米颗粒光催化甘油水溶液制氢的性能,3%Bi、S共掺杂TiO2具有最高的产氢速率,在紫外光和模拟太阳光照射下,其产氢速率可分别达到1 514.9和190.2μmol/(h·g)。

A series of Bi,S-codoped TiO2 nanoparticles with different Bi（ S） /Ti molar ratios were synthesized by a sol-gel method. The effects of Bi,S content on the morphology,textural properties,photo absorption and photocatalytic activity of TiO2 nanoparticles were investigated. SEM,TEM,XRD,FT-Ranman,UV-vis,and XPS observations of the obtained samples revealed the formation of anatase TiO2 nanopaticles doped with Bi and S,which existed as Bi2O3 and SO4^2-,respectively. The doping of Bi and S could decrease the diameter of TiO2 nanoparticles. Bi-doped TiO2 samples showed an extension of light absorption into the visible region,which mainly originated from the doping process with the formation of new energy level of Bi ion. The addition of S could improve photocatalytic activities by increasing the acidic sites of the catalyst. The co-doping Bi and S strongly affected photocatalytic performance of TiO2 nanoparticles. Under the same conditions,the TiO2 nanoparticles doped with Bi and S exhibited a higher photocatalytic activity for H2 evolution from glycerol /water mixtures than the bare TiO2 nanoparticles.TiO2nanoparticles doped with 3% Bi and S had a maximum H2 production rate of 1 514. 9 and190. 2 μmol /（ h·g） under UV and solar light irradiation,respectively.