In-Au(111)和Ir-Au(111)合金表面的性质及其对巴豆醛的吸附比较

采用密度泛函理论研究了M（M=In，Ir）原子修饰的M-Au（111）合金表面的稳定性，并选其最优模型探讨了合金表面的活性及其对巴豆醛的吸附。合金的几何构型、形成能和结合能等性质表明，In-Au（111）面的稳定性随In原子的间距增大而提高，Ir-Au（111）面的稳定性随Ir原子的间距增大而降低。对于巴豆醛在MAu（111）面上的吸附，当其通过C＝O吸附于合金表面的Top_M位时，吸附能最大，吸附构型最稳定。从巴豆醛的结构变化、态密度、差分电荷密度以及Mulliken电荷布居等分析可以看出，稳定吸附构型的巴豆醛分子形变较大，电荷转移明显。其中，位于-7.04 eV至费米能级处的p、d轨道杂化，对体系的吸附具有重要贡献。分析比较In-Au（111）面与Ir-Au（111）面，发现后者的配体效应更佳，不仅具有更高的稳定性和活性，而且对于巴豆醛具有更强的吸附力。此外，相比于改性前的Au（111）面，M原子的修饰明显提升了金属表面的稳定性及吸附能力。

Comparison of Properties of In-Au(111) and Ir-Au(111) Alloy Surfaces,and Their Adsorption to Crotonaldehyde

The stability of M-Au(111) surfaces modified by M (M=In, Ir) was investigated using density functional theory. The most favorable model was selected to explore the chemical reactivity and adsorption of crotonaldehyde. The stability of the M-Au(111) surfaces was calculated using geometric configuration, and formation and cohesive energies. The calculations showed that the stability of the In-Au(111) surface increased as the atomic spacing of In was increased. Conversely, the Ir-Au(111) showed the opposite trend. The adsorption at the Top_M site was most stable when the crotonaldehyde on the M-Au(111) surfaces interacting via the C=O. Additionally, the adsorption energies were at their maximum. A combination of structural changes, density of state, deformation density and Mulliken charge analysis showed that the deformation of crotonaldehyde was larger than other adsorption modes, with an obvious charge transfer. Additionally, p and d orbital hybridization between -7.04 eV to Fermi level was found to have an important contribution to the adsorption process. Compared with the Au(111) surface, the stability and adsorption capacity of the M-Au(111) surfaces were significantly improved following modification by M atoms. Importantly, the Ir-Au(111) surface was found to have higher stability and activity, and stronger adsorption of crotonaldehyde than the In-Au(111) surface.