高等学校化学学报

高等学校化学学报

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Zn(Ⅱ)在TiO2表面上的微观吸附模式研究

杨玉环1, 潘纲1, 马骁楠2, 陈灏1, 张美一1, 何广智1, 李薇1   

    1. 中国科学院生态环境研究中心环境水质学国家重点实验室, 北京 100085;
    2. 中国海洋大学海洋化学理论与工程技术教育部重点实验室, 青岛 266003
  • 收稿日期:2007-11-13 修回日期:1900-01-01 出版日期:2009-02-10 发布日期:2009-02-10
  • 通讯作者: 潘纲

Study of Microscopic Adsorption Modes of Zn(Ⅱ) on TiO2 Surface

YANG Yu-Huan1, PAN Gang1*, MA Xiao-Nan2, CHEN Hao1, ZHANG Mei-Yi1, HE Guang-Zhi1, LI Wei1   

    1. State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China;
    2. Key Laboratory of Marine Chemistry Theory and Technology; Ministry of Education; Ocean University of China, Qingdao 266100, China
  • Received:2007-11-13 Revised:1900-01-01 Online:2009-02-10 Published:2009-02-10
  • Contact: PAN Gang

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摘要： 用延展X射线吸收精细结构(EXAFS)技术并结合密度泛函理论(DFT)研究了Zn(Ⅱ)在锐钛型TiO2表面上微观吸附结构。EXAFS结果表明, Zn(Ⅱ)在吸附时由自由水合状态下的Zn—O六配位八面体结构向四配位四面体结构转化, 中心Zn原子的第二配位层存在两种不同的Zn—Ti距离(R1=0.371和R2=0.332 nm). 用DFT方法对四配位水合Zn离子在簇Ti2O11H14上进行优化后发现, 四配位的Zn—O平均距离为0.200 nm; 外层Zn—Ti结合存在两种稳定的吸附模式: 单角吸附模式和更加稳定的双角吸附模式, 其Zn—Ti距离分别为0.369和0.335 nm. EXAFS结果与DFT计算结果吻合, 说明Zn(Ⅱ)在锐钛型TiO2表面上存在不同的亚稳平衡态吸附结构.

关键词: 延展X射线吸收精细结构, 密度泛函理论, 水合Zn离子, 锐钛型TiO2, 亚稳平衡态, 吸附

Abstract: Microscopic adsorption modes of Zn(Ⅱ) on anatase TiO2-water interface were studied using extended X-ray absorption fine structure(EXAFS) spectroscopy. Quantitative analysis of the EXAFS spectra showed that the microscopic structure of Zn(Ⅱ) on anatase TiO2 is four coordinate complex, and there are at least two types of bonding based on the average Ti—Zn distances in the second sphere. Two different geometry configurations of single-corner(SC) and double-corner(DC) for adsorption on the(101) surface cluster were calculated using DFT method. The Zn—Ti distances are 0.369 nm and 0.335 nm for the single-corner adsorption mode and double-corner adsorption mode, respectively. Therefore, the EXAFS fitting data, R1=0.371 nm, R2=0.332 nm, can be well distinguished for SC and DC mode respectively. The calculation results also showed that the optimized Zn—O average distance of Zn—O tetrahedron is about 0.200 nm, which agree with the EXAFS results. These show that Zn was adsorbed onto TiO2 surfaces in different metastable equilibrium state(MEA) under the same thermodynamic conditions.

Key words: Extended X-ray absorption fine structure(EXAFS), Density functional theory, Hydrated Zn, Anatase TiO2, MEA state, Adsorption

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