金属簇X(X=Pt-Au, Au-Au)负载在(3×2) TiO_2(110)完整表面上的覆盖度效应(英文)  

Coverage-Dependent Adsorption of X Clusters(X=Pt-Au,Au-Au) on the Defect-Free(3×2) TiO_2(110) Surface

作　　者：赵伟娜[1] 林华香[2] 李奕[1] 章永凡[1] 黄昕[1] 陈文凯[1,2] 

机构地区：[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

出　　处：《物理化学学报》2012年第8期1861-1868,共8页Acta Physico-Chimica Sinica

基　　金：supported by the National Natural Science Foundation of China (90922022);Natural Science Foundation of Fujian Province,China(2012101032,2012101041);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.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.

关 键 词：密度泛函理论:TiO2(110)表面:双金属簇 

分 类 号：O614.411[理学—无机化学]