Theoretical investigation of the effect of phosphate doping on the aggregation of Au atoms on an Al2O3 (0001) surface-猫眼课题宝

DOI：

10.1016/j.apsusc.2018.09.172

发表时间：

2019-01

期刊：

Applied Surface Science

影响因子：

6.7

通讯作者：

中科院分区：

材料科学1区

文献类型：

作者：

K. Tada;H. Koga;Hiroaki Sakurai;Shingo Tanaka;Yoshinori Ato;Akihide Hayashi;T. Kawakami;S. Yamanaka;M. Okumura

利用密度泛函理论，研究了金原子和金二聚体在具有不同磷酸盐覆盖率的 α-Al2O3(0001) 表面上的吸附。当磷酸盐覆盖率较低（0％或25％）时，Au二聚体比表面上孤立的Au原子更稳定，因此，Au原子聚集成Au二聚体是放热的。相反，当磷酸盐覆盖率较高（50％或100％）时，孤立的Au原子比表面上的Au二聚体更稳定，并且Au原子聚集是吸热的。这种差异是由相邻磷酸基团之间的距离差异造成的；在一定距离下，磷酸基团能够桥接金原子。 Au 二聚体在磷酸盐-磷酸盐桥位点处的 Au-Au 键因空穴从 Al2O3 表面转移到 Au 二聚体的键合 σ 轨道而变得不稳定。孤立的磷酸基团不会导致不稳定。这些结果很好地解释了Al2O3表面磷酸盐掺杂抑制Au颗粒聚集的机制，并表明电荷从表面转移到Au原子对于抑制Au烧结的重要性。

Using density functional theory, the adsorption of Au atoms and Au dimers onto α-Al2O3(0001) surfaces with various phosphate coverages was investigated. When the phosphate coverage is low (0% or 25%), Au dimers are more stable than isolated Au atoms on the surfaces, and therefore, aggregation of Au atoms into Au dimers is exothermic. In contrast, when the phosphate coverage is high (50% or 100%), isolated Au atoms are more stable than Au dimers on the surface, and Au atom aggregation is endothermic. This difference is caused by differences in the distance between adjacent phosphate groups; at certain distances, the phosphate groups are capable of bridging Au atoms. The Au-Au bond of a Au dimer at a phosphate-phosphate bridge site is destabilized by hole transfer from the Al2O3surfaces to the bonding σ orbital of the Au dimer. Isolated phosphate groups cannot cause the destabilization. These results provide a good explanation for the mechanism of the suppression of aggregation of Au particles caused by phosphate doping on an Al2O3surface, and show the importance of charge transfer from a surface to Au atoms for suppressing Au sintering.

Theoretical investigation of the effect of phosphate doping on the aggregation of Au atoms on an Al2O3 (0001) surface

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