Ag掺杂TiO_2纳米晶粉体的制备及性能表征

Preparation and Characterization of Ag-doped TiO_2 Nanocrystalline Powders

以钛酸丁酯、无水乙醇、硝酸银等为原料,通过溶胶-凝胶法制备了不同Ag掺杂含量的TiO_2纳米晶粉体,用X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)检测分析了粉体的晶型转化、微观形貌和晶粒尺寸,用光致发光光谱(PL)表征材料的光电性能。结果表明,Ag掺杂后的TiO_2纳米晶粉体的锐钛矿相比未掺杂Ag样品的含量有所增多,当Ag掺杂量为1%和3%时,锐钛矿的相对含量约为65%;随着Ag掺杂量的增加,锐钛矿晶粒尺寸逐渐减小;由TEM图像可知,Ag颗粒较为均匀地弥散在TiO_2纳米晶粉体中;由PL荧光检测结果可知,Ag掺杂TiO_2纳米晶粉体的荧光强度比未掺杂的TiO_2纳米晶粉体的低。试验结果表明,Ag颗粒较为均匀地弥散在TiO_2纳米晶粉体中,有利于在锐钛矿界(表)面形成Ti-O-Ag的键合,有效阻止锐钛矿向金红石的转变,同时抑制锐钛矿TiO_2纳米晶粒的增长,Ag颗粒与TiO_2纳米晶粉体接触形成肖特基势垒,加速光生电子由TiO_2向Ag颗粒传输,减小光生电子与空穴的复合几率,从而提高TiO_2纳米晶粉体的光电性能。

Ag-doped TiO2nanocrystalline powders were prepared by sol-gel method using butyl titanate,absolute ethanol,silver nitrate as the raw material.The crystal form transformation of the powders was analyzed by X - ray diffraction (XRD),and the microstructure of the powder was characterized by scanning electron microscopy (SEM)and transmission electron microscopy(TEM),and the photoluminescence spectra(PL)were used to characterize the photoelectric properties of the material.It is shown that the content of anatase in Ag-doped TiO2nanocrystalline powders is increased compared with that in undoped Ag sample. The relative content of anatase is about 65% when the Ag doping amount is 1%and 3%.With the increase of Ag doping,the grain size of anatase decreases.The TEM images show that Ag particles are more uniform dispersed in the TiO2nanocrystalline powders,and PL fluorescence detection shows that the fluorescence intensity of Ag-doped TiO2 nanocrystalline powders islower than that of undoped TiO2 nanocrystalline powders.Ag particles are dispersed more evenly in the TiO2 nanocrystalline powders, which is favorable for the formation of Ti-O-Ag bondson the anatase surface and effectively prevents the transformation of anatase to rutile while inhibiting the growth of nano-TiO2nanocrystalline,the contact between Ag particles and TiO2 nano-crystalline powder to form Schottky barrier accelerates the transformation of photogenerated electron from TiO2to Ag particles,reduces the recombination probability of photogenerated electrons and holes,and the optical properties of the powder are enhanced at the same time.