Au@TiO_2核壳纳米粒子光催化过程的表面增强拉曼光谱研究  

In-situ Surface Enhanced Raman Spectroscopic Investigation of Photocatalysis at Au@TiO_2 Surface

作　　者：刘伟[1] 郭清华[1] 秦维[1] 姚建林[1] 顾仁敖[1] 

机构地区：[1]苏州大学材料与化学化工学部,苏州215123

出　　处：《高等学校化学学报》2011年第8期1865-1869,共5页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:20973120;21073128);江苏省自然科学基金(批准号:BK2005032)资助

摘　　要：利用聚电解质的静电吸附作用(层层组装),在Au纳米粒子表面包裹上不同层数的二氧化钛前驱体二(2-羟基丙酸)二氢氧化铵合钛(TALH),通过退火形成Au@TiO2复合纳米粒子.以苯硫酚(TP)作为探针分子对退火前复合纳米粒子不同壳层厚度的SERS效应进行表征.研究发现,SERS信号强度的变化与壳层厚度密切相关,当Au表面包裹至3层TALH时,信号几乎完全消失.结合紫外照射,利用SERS对亚甲基蓝(MB)在TiO2壳层表面的光催化降解过程进行了研究.结果表明,MB的降解主要经历了从多体及二聚体吸附逐渐向单体吸附方式的转变,然后又经历了一个脱甲基过程.Based on the polyelectrolyte-mediated electrostatic adsorption（layer by layer method）,Au@TiO2 core shell nanoparticles were prepared through the modification of the different layers of bis（ammonium lactate）titanium dihydroxide（TALH） on Au nanoparticles followed with a calcination.By using thiophenol as probe,the surface enhanced Raman scattering（SERS） effect was observed from Au nanoparticles attached with the TiO2 precursor.The SERS effect was dependent on the shell thickness.After coated with three layers of TALH,SERS effect from the Au nanoparticles core disappeared.The photocatalytic processes of methylene blue（MB） was investigated on Au@TiO2 by in-situ SERS under UV illumination.The observation of C—N—C skeleton deformation vibrational mode at 450 and 504 cm-1 indicated that MB adsorbed on the Au@TiO2 surface in a dimmer or polymer formation at the initial stage.With the increase of the UV illumination time,the band at 481 cm-1assigned to the monomer of MB was enhanced and the bands at 1180 and 1073 cm-1 assigned to the C—H relevant vibrational modes disappeared.It indicated that the photocatalytic degradation of MB on Au@TiO2 underwent the transformation of dimmer or polymer to the monomer initially,followed with the degradation of methyl group.Results indicate in-situ SERS technique combined with UV illumination might be developed as one of powerful tools for monitoring the photocatalytic reactions.

关 键 词：Au@TiO2核壳纳米粒子 表面增强拉曼光谱 层层组装技术 光催化 机理 

分 类 号：O646[理学—物理化学]