Single atom alloys (SAAs) have proven to be effective catalysts, offering customizable properties for diverse chemical processes. Various metal combinations are used in SAAs and Pd dispersed materials are frequently employed in catalyzing hydrogenation reactions. Herein, we explore the hydrogenation of phenylacetylene to styrene and ethylbenzene on PdAg SAA using density functional theory calculations. Our results show that while PdAg SAA does improve the activity of the host Ag towards hydrogenation, a dilute PdAg SAA surface with isolated Pd-atoms is not selective towards partial hydrogenation of phenylacetylene. Additionally, we investigate how the size of the reactant molecule, the size of the metal alloy ensemble, and the ligand effect impact the hydrogenation process. The SAA enhances the binding strengths of various organic adsorbates, although this effect diminishes as the adsorbate size increases. Our findings indicate the dilute PdAg exhibits selectivity towards hydrogenation of smaller molecules such acetylene due to its distinct adsorption geometry. The selective hydrogenation of phenylacetylene necessitates a surface Pd dimer ensemble. Our research highlights the importance of both reactant molecule size and surface configurations in SAA catalysts. This is particularly crucial when dealing with the adsorption of sizable organic molecules where the functional group can adopt different adsorption modes.

中文翻译：

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了解 PdAg 单原子合金上苯乙炔的选择性氢化：DFT 对分子尺寸和表面整体效应的见解


单原子合金 (SAA) 已被证明是有效的催化剂，可为各种化学过程提供可定制的特性。 SAA 中使用了各种金属组合，并且 Pd 分散材料经常用于催化氢化反应。在此，我们利用密度泛函理论计算探索了 PdAg SAA 上苯乙炔氢化成苯乙烯和乙苯的过程。我们的结果表明，虽然 PdAg SAA 确实提高了主体 Ag 的氢化活性，但具有孤立 Pd 原子的稀释 PdAg SAA 表面对苯乙炔的部分氢化没有选择性。此外，我们还研究了反应物分子的大小、金属合金整体的大小以及配体效应如何影响氢化过程。 SAA 增强了各种有机吸附物的结合强度，尽管这种效果随着吸附物尺寸的增加而减弱。我们的研究结果表明，由于其独特的吸附几何形状，稀释的 PdAg 对乙炔等较小分子的氢化具有选择性。苯乙炔的选择性氢化需要表面钯二聚体整体。我们的研究强调了 SAA 催化剂中反应物分子大小和表面构型的重要性。这在处理相当大的有机分子的吸附时尤其重要，其中官能团可以采用不同的吸附模式。