γ-Al2O3 和 Sn 改性 γ-Al2O3 上 Pt 团簇从头算分子动力学研究,The Journal of Physical Chemistry C

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γ-Al2O3 和 Sn 改性 γ-Al2O3 上 Pt 团簇从头算分子动力学研究
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2023-09-26 , DOI: 10.1021/acs.jpcc.3c04595
Tso-Hsuan Chen ₁ , Dionisios G. Vlachos _{1,

2} , Stavros Caratzoulas ₂

Affiliation

我们进行了 AIMD 自由能模拟，以研究干 γ-Al ₂ O ₃ (100)、干γ-Al 2 O 3 (110) 和湿γ-Al _{2 O}_{3 (110) 上 Pt 原子和 Pt}_n ( n = 2–3) 物质的动力学γ-Al ₂ O ₃ (110) 表面，OH 覆盖度对应于 500 K (11.8 OH/nm ² ) 和 800 K (5.9 OH/nm ^{2 )}），同时改变 Pt 和 Sn 的负载量。在相同的干燥条件和温度下，比较（100）和（110）表面终端表明，Pt 和表面之间的相互作用在确定还原的 Pt 原子之间的平均力是否具有排斥力方面起着至关重要的作用，如在(100) 表面，或者是否可以支持结合的 Pt-Pt 态，如在 (110) 表面上观察到的。(110)表面的水合作用具有显着影响。在Pt负载量为0.75 Pt/nm ²、水合作用为5.9 OH/nm ²时，平均力势能增加。尽管仍然支持 Pt-Pt 束缚态，但它在动力学上变得更难从分散态接近。水负载量更高（11.8 OH/nm ^2），平均力的 Pt-Pt 势变得主要是排斥性的，并且不再能够维持 Pt-Pt 束缚态。^{1.12 Pt 原子/nm 2}的较高 Pt 负载量促进 Pt 聚集成逐渐增大的簇，但高水平的水合作用会在动力学上阻碍颗粒生长。在 Sn 改性的 γ-Al ₂ O ₃ (110) 上，Pt 倾向于与 Sn 缔合，除非在高水平的表面水合下，其中 Pt 和 Sn 原子之间的平均力势能变得排斥。Sn的存在抑制了Pt颗粒的聚集，并且随着Sn负载量的增加，平均力的Pt-Pt势变得越来越排斥。

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Ab Initio Molecular Dynamics Study of Pt Clustering on γ-Al2O3 and Sn-Modified γ-Al2O3

We have conducted AIMD free energy simulations to examine the dynamics of Pt atoms and Pt_n (n = 2–3) species on dry γ-Al₂O₃(100), dry γ-Al₂O₃(110), and wet γ-Al₂O₃(110) surfaces, with OH coverages corresponding to 500 K (11.8 OH/nm²) and 800 K (5.9 OH/nm²), while varying the Pt and Sn loading. Under the same dry conditions and temperature, comparing the (100) and (110) surface terminations revealed that the interactions between Pt and the surface play a crucial role in determining whether the potential of mean force between reduced Pt atoms is repulsive, as observed on the (100) surface, or if it can support a bound Pt–Pt state, as observed on the (110) surface. The hydration of the (110) surface had a significant impact. At a Pt loading of 0.75 Pt/nm², with hydration of 5.9 OH/nm², the energy of the potential of mean force increases. Although a Pt–Pt bound state is still supported, it becomes kinetically less accessible from the dispersed state. At an even higher water loading of 11.8 OH/nm², the Pt–Pt potential of mean force becomes predominantly repulsive and can no longer sustain the Pt–Pt bound state. Higher Pt loadings of 1.12 Pt atoms/nm² promote the aggregation of Pt into progressively larger clusters, but high levels of hydration can kinetically impede particle growth. On Sn-modified γ-Al₂O₃(110), Pt tends to associate with Sn, except at high levels of surface hydration where the potential of mean force between Pt and Sn atoms becomes repulsive. The presence of Sn inhibits the aggregation of Pt particles, and the Pt–Pt potential of mean force becomes increasingly repulsive with higher Sn loading.

更新日期：2023-09-26

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