Changes in Surface Oxygen Vacancy Formation Energy at Metal/Oxide Perimeter Sites: A Systematic Study on Metal Nanoparticles Deposited on an In2O3(111) Support
Changes in Surface Oxygen Vacancy Formation Energy at Metal/Oxide Perimeter Sites: A Systematic Study on Metal Nanoparticles Deposited on an In2O3(111) Support
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DOI：
10.1021/acs.jpcc.0c10010
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发表时间：
2020-12-17
影响因子：
3.7
通讯作者：
Kamachi, Takashi
中科院分区：
文献类型：
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作者：
Hinuma, Yoyo;Toyao, Takashi;Kamachi, Takashi
金属/氧化物载体周边位点可以提供独特的性质，因为载体表面上的局部环境被附近的金属改变。本研究模拟了当金属纳米棒代替纳米颗粒吸附在In 2 O3载体的（111）表面上时的周界位点。金属元素M是Ag、Au、Cu、Ir、Pd、Pt和Re中的一种。在相同的近似值和条件下，使用系统的第一性原理计算评估了纳米棒吸附的表面氧空位形成能（EOvac）的变化，发现由两个主要因素驱动。首先，如果金属的费米能比表面O空位的缺陷能级更深，则金属可以充当电子清除剂，以在从靠近金属的位点去除O时接受过量的电子。每个M的最小EOvac与O去除后向纳米棒的Bader电荷转移非常好地相关。没有发现O去除后纳米棒的几何弛豫效应，因为O去除后纳米棒原子几乎没有任何自发重排。结果表明，随着M的功函数的增大，表面的最小EOvac趋于减小。第二，在同一表面上的不同O位中，当存在与吸附金属的界面态时，在高于载体的价带的能级处，O位中的EOvac较低。这些见解将有助于规划战略，以获得积极的O网站。
Metal/oxide support perimeter sites can provide unique properties because the local environment on the support surface is changed by the nearby metal. This study modeled perimeter sites when metal nanorods were adsorbed in lieu of nanoparticles on the (111) surface of an In2O3 support. The metal element M was one of Ag, Au, Cu, Ir, Pd, Pt, and Re. Changes in the surface oxygen vacancy formation energy (EOvac) with nanorod adsorption were evaluated using systematic first-principles calculations under the same approximations and conditions and were found to be driven by two major factors. First, if the Fermi energy of the metal is deeper than the defect energy level of surface O vacancies, the metal may act as an electron scavenger to accept excess electrons upon O removal from sites close to the metal. The minimum EOvac for each M correlated very well with the Bader charge transfer to the nanorod upon O removal. The effect of geometrical relaxation of the nanorod after O removal was not found because there was barely any spontaneous rearrangement of nanorod atoms after O removal. As a consequence, the minimum EOvac in a surface tends to decrease with the increasing work function of M. Second, among different O sites on the same surface, EOvac is lower in O sites when there are interface states with the adsorbed metal at energy levels higher than the valence band of the support. These insights would help in planning strategies to obtain active O sites.