物理化学学报 >> 2012, Vol. 28 >> Issue (08): 1861-1868.doi: 10.3866/PKU.WHXB201205214

理论与计算化学 上一篇    下一篇

金属簇X (X=Pt-Au, Au-Au)负载在(3×2) TiO2(110)完整表面上的覆盖度效应

赵伟娜1, 林华香2, 李奕1, 章永凡1, 黄昕1, 陈文凯1,2   

  1. 1. 福州大学化学化工学院, 福州 350116;
    2. 福州大学省部共建光催化国家重点实验室培育基地, 福州 350002
  • 收稿日期:2012-03-20 修回日期:2012-05-21 发布日期:2012-07-10
  • 通讯作者: 陈文凯 E-mail:qc2008@fzu.edu.cn
  • 基金资助:

    国家自然科学基金(90922022)和华中科技大学煤燃烧国家重点实验室开放基金(FSKLCC1110)资助项目

Coverage-Dependent Adsorption of X Clusters (X=Pt-Au, Au-Au) on the Defect-Free (3×2) TiO2(110) Surface

ZHAO Wei-Na1, LIN Hua-Xiang2, LI Yi1, ZHANG Yong-Fan1, HUANG Xin1, CHEN Wen-Kai1,2   

  1. 1. College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350116, P. R. China;
    2. Fujian Provincial Key Laboratory of Photocatalysis-State Key Laboratory Breeding Base, Fuzhou University, Fuzhou 350002, Fujian, P. R. China
  • Received:2012-03-20 Revised:2012-05-21 Published:2012-07-10
  • Contact: CHEN Wen-Kai E-mail:qc2008@fzu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (90922022) and Foundation of State Key Laboratory of Coal Combustion of Huazhong University of Science and Technology, China (FSKLCC1110).

摘要:

采用自旋极化密度泛函和广义梯度近似的方法并结合周期平板模型, 探讨了不同覆盖度(θ)下双金 属簇X (X=Pt-Au, Au-Au)在(3×2)TiO2(110)完整表面上的吸附行为. 另外, 在本文给出的所有覆盖度模式下(θ= 1/6-1 ML), 我们仅研究其基态构型. 计算结果表明: 当θ<1/2 ML时, 金属簇X在TiO2(110)表面上吸附能随覆盖 度的增加而增加; 当θ>1/2 ML时, 除了饱和覆盖度下, 吸附能随覆盖度的增加而减小; 当θ=1/2 ML时, 吸附能最 大. 即使Pt-Au/TiO2体系的吸附能比Au-Au/TiO2体系的小, 但相对于Au-Au 簇, Pt-Au 簇更容易在TiO2(110)表 面上形成双金属单分子层. 在半覆盖和全覆盖下, X簇的峰与TiO2的峰在-3.0 eV到费米能级之间产生明显重 叠, 表明簇与底物之间存在化学作用. 且当覆盖度小时, X-TiO2相互作用是成簇的主要因素; 随着覆盖度的增 大, X-X原子间相互作用就逐渐变成了成簇的主要动力.

关键词: 密度泛函理论, TiO2 (110)表面, 双金属簇

Abstract:

Based on spin-polarized density functional theory and generalized gradient approximation (DFT-GGA) calculations, the coverage-dependent adsorption of X bimetallic clusters (X=Pt-Au, Au-Au) on the (3 × 2) TiO2(110) surface has been investigated utilizing periodic supercell models in the absence of oxygen vacancy sites. Only the ground-state structures corresponding to the given coverage patterns (θ= 1/6-1 ML) for X clusters are discussed in this work. The unambiguous results reveal that the adsorption energies increase with coverage up to 1/2 ML and then decrease except for when saturated coverage is reached. According to the interaction with X clusters, it is more feasible at all coverage levels to create a monolayer film of Pt-Au bimetallic clusters on the TiO2(110) surface than it is to create a monolayer of Au- Au clusters, even though the adsorption energy of the Pt-Au/TiO2 adsorption system is smaller in comparison with that of the Au-Au/TiO2 system. Importantly, especially for the half and saturated coverages, there is a broadening of X peaks overlapping with the TiO2 state ranging from -3.0 eV to the Fermi level, suggesting a strong interaction between the surface and bimetallic cluster. Also of particular interest is the adsorptive mechanism where the X-TiO2 interaction is the main driving force at the initial stage of the adsorption process, whereas the X-X interaction controls the process as the coverage increases.

Key words: Density functional theory, TiO2 (110) surface, Bimetallic cluster

MSC2000: 

  • O641