微波载银对纳米二氧化钛相变及光催化性能的增效作用

用微波法制备系列载Ag纳米TiO2，发现微波载Ag对纳米TiO2的相变和光催化活性具有增效作用。采用X-射线粉末衍射(XRD)，透射电镜(TEM)，X-射线光电子能谱仪(XPS)，激光Raman光谱及漫反射光谱(DRS)方法对比研究纳米TiO2与载Ag纳米TiO2的性质。结果表明，所制得载Ag纳米TiO2是以锐钛矿为主相的混晶，平均粒径约为10 nm，负载Ag促进纳米TiO2中锐钛矿相转化金红石相相变，减小纳米晶尺寸，并使纳米TiO2光响应范围向可见光区移动 6 nm。在低浓度范围，微波法能均匀地将Ag负载于纳米TiO2表面，并以Ag0/Ag+的形式存在，抑制光生电子与光生空穴复合，大大地提高了纳米TiO2光催化活性。在近紫外-可见光照射下，载Ag量为0.05 mol %的纳米TiO2对罗丹明B的光催化降解效果最好。

Synergistic Effects of Microwave Doped-Ag on the Phase Transformation and Photocatalytic Activity of Titania Nanocrystallite

A series of Ag-doped titania nanocrystallites were prepared by the microwave treatment. It was found that the microwave-treated Ag-doped plays synergistic effect on the phase transformation and the photocatalytic activity of titania nanocrystallite. The pure titania nanocrystallites and the silver-doped titania nanocrystallites were analyzed by X-ray diffraction (XRD), transmission eletron microscope (TEM), X-ray photoelectron spectrophotometer (XPS), Raman spectroscopy and diffuse reflectance spectrophotometer (DRS) to determine their physicochemical characteristics. The results showed that the Ag-doped titania nanocrystallite with an average diameter of 10 nm contained anatase as the main phase and rutile phase. Itwas found that the Ag dopant promoted the formation of the rutile phase, reduction the size crystallite of titania nanocrystallite, and the photoresponse of titania nanocrystallite was red-shifted about 6 nm to the visible region. For the doped Ag, the species of Ag0/Ag+ were found on the surface of titania nanocrystallite in a highly dispersed state, within a relative low concentration range. The Ag-doped titania nanocrystallites can effectively capture the photoinduced elctrons and holes, resulting in drastic enhancement of the photocatalytic activity, which was evaluated by measuring the decomposition rates of Rhodamine B exposed to the near ultraviolet-visible light radiation. For the Ag-doped titania nanocrystallite, the highest degradation ratio was observbed with the Ag content of 0.05 mol %.