TiO2表面吸附三氟乙酸的密度泛函理论研究  

Study on Trifluoroacetic Acid Adsorbed on TiO_2 Surface with Density Functional Theory

作　　者：崔文颖[1] 刘子忠[1] 蒋亚军[1] 王娜[1] 封继康[2] 

机构地区：[1]内蒙古自治区绿色催化重点实验室、化学与环境科学学院、内蒙古师范大学,呼和浩特010022 [2]理论与计算化学国家重点实验室吉林大学,长春130023

出　　处：《化学学报》2012年第19期2049-2058,共10页Acta Chimica Sinica

基　　金：国家自然科学基金(No.21063009);内蒙古自然科学基金(2012MS0218);内蒙古人才基金资助~~

摘　　要：探求全氟羧酸(Perfluorinated Carboxylic Acids,PFCAs)的降解方法及其降解机理是当前亟待解决的问题.基于密度泛函理论的Materials Studio(MS)程序包中的CASTEP计算程序,优化了锐钛矿TiO2(101),(001),(110),(210);金红石TiO2(110),(001),(101),(210)和板钛矿TiO2(210),(101),(001),(110)晶面的几何结构,结果发现锐钛矿(101)晶面、金红石(110)晶面和板钛矿(210)晶面的能量最低,为最稳定的吸附面.对在最稳定三种TiO2吸附面上吸附三氟乙酸(Trifluoroacetic Acid,TFA)的18种吸附方式优化结构的吸附能计算表明,TFA被垂直吸附在板钛矿型TiO2(210)表面且羧基端H被Ti原子吸附的吸附方式吸附能最大,吸附结构最稳定,为TFA在TiO2表面吸附的最佳方式.分态密度计算表明,板钛矿(210)面与TFA间存在弱的共价相互作用,吸附后其表面结构的带隙因TFA中的O和F的2p轨道进入,带隙由吸附前的3.06 eV降低到吸附后的2.80 eV,光催化吸收波长由吸附前的385 nm增加到吸附后的443 nm,提高了可见光的吸收效率.The method and mechanism on the perfluorinated carboxylic acids （PFCAs） degradation is a hot issue. The crystal lattice structures of the anatase TiO2（101）, （001）, （110）, （210）, the rutile TiO2（110）, （001）, （101）, （210） and the brookite TiO2 （210）, （101）, （001）, （110） were optimized with the CASTEP program in Materials Studio package based the density functional theory （DFT）. It is found that the energies of the anatase （101）, rutile （110） and brookite （210） are the lowest, and the most stable adsorption surfaces, respectively. The adsorption energies of the 18 kinds of the optimized modes on the most stable TiO2 surfaces adsorbed by trifluoroacetic acid （TFA） were calculated. It is indicated that the absorption energy of the mode which the TFA is perpendicular to the brookite （210） surface and the carboxyl group of H adsorbed by Ti atom on the brookite （210） is the biggest, and the adsorption structure is the most stable, and the adsorption mode is the best. The partial state densities for the three kinds of the most stable absorption modes were calculated. It is revealed that the covalent interac- tion of the TFA on bookite （210） surface is weak, resulted from the narrowing of the band gap that the 2p orbital of O, F of TFA inserts into between the valence band （VB） and conduction band for TiO2. In the best adsorption mode, before and after adsorption the band gap goes down from 3.06 eV to 2.80 eV, i.e., photocatalytic wavelength increases from 385 nm to 443 nm, so that the visible light absorption efficiency is increased.

关 键 词：CASTEP 二氧化钛 三氟乙酸 吸附 密度泛函 

分 类 号：O614.411[理学—无机化学]