First-principles theoretical studies of Pt_n (n = 1–7) clusters supported on pristine α-Al₂O₃ (0001) and embedded in vacancies in the alumina surface have been carried out to investigate the effect of embedding and overcoating on coking, sintering, and catalytic activity. The hydrogen adsorption energy and the ethylene adsorption energy are used as proxies for estimating the cluster’s relative activity for C–H bond activation and coking. The embedded clusters are found to exhibit enhanced stability, indicating that they are less prone to sintering. The hydrogen and ethylene adsorption energy of platinum clusters supported on pristine α-Al₂O₃ are found to be correlated, suggesting that an increase in activity will also cause an increase in coking. Embedded clusters offer a pathway to maintain the catalytic activity while reducing the coking. Embedding the clusters makes the platinum more negatively charged, which repels ethylene, minimizing a critical pathway that leads to coking. The studies provide microscopic insight into the reduced coking in overcoated catalysts and offer a pathway toward reducing coking and sintering while maintaining the activity of the catalyst.

中文翻译：

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在氧化铝中嵌入铂簇对烧结，焦化和活性的影响

第一原理的Pt的理论研究_Ñ（Ñ = 1-7）簇支撑在原始的α-Al ₂ ö ₃（0001）并嵌入在氧化铝表面已经进行了调查嵌入和复涂上焦化的效果空缺，烧结和催化活性。氢吸附能和乙烯吸附能被用作估算簇对C–H键活化和焦化的相对活性的代表。发现嵌入的团簇表现出增强的稳定性，表明它们不易烧结。支撑在原始铂簇的氢和乙烯的吸附能量的α-Al ₂ ö ₃被发现是相关的，表明活性的增加也将导致焦化的增加。嵌入的团簇提供了一种途径，可在降低焦化的同时保持催化活性。嵌入簇使铂带更多的负电荷，从而排斥乙烯，最大程度地减少了导致焦化的关键途径。这些研究提供了微观的见解，以了解过度涂覆的催化剂中减少的焦化，并提供了在保持催化剂活性的同时减少焦化和烧结的途径。