Ostwald ripening microkinetic simulation of Au clusters on MgO(0 0 1)
Ostwald ripening microkinetic simulation of Au clusters on MgO(0 0 1)
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DOI：
10.1016/j.apsusc.2021.151317
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发表时间：
2022-01
影响因子：
6.7
通讯作者：
Samantha Francis;A. Boucher;Glenn Jones;A. Roldan
中科院分区：
文献类型：
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作者：
Samantha Francis;A. Boucher;Glenn Jones;A. Roldan
烧结是导致负载型金属纳米颗粒催化剂失去活性的最常见的过程之一。我们采用自底向上的方法，结合从头算和微动力学模拟，研究了MgO（0 0 1）上支持的Au团簇的消化和生长机制。在干净的MgO表面上扩散单个金原子的能垒为0.29 eV，与先前的报道完全一致。此外，作为与奥斯特瓦尔德机制相关的整个能量分布的延伸，我们发现在所调查的情况下，所有的活化能都低于1.05 eV。在成熟过程中观察到奇偶团簇趋势，这归因于与单个金原子相关的未配对电子配对的稳定性。微动力学分析表明，在160 K温度下，氧化镁表面仍存在Au单原子。在较高的温度下，该系统有足够的能量使单个原子在表面扩散并附着在其他原子或簇上。在类似于室温的温度下，团簇成熟形成更大的颗粒，以达到更稳定的平衡。
Sintering is one of the most common processes responsible for the loss of supported metal nanoparticle catalysts' activity. We have combined ab-initio calculations with microkinetic simulations to investigate the digestion and growth mechanism on Au clusters supported on MgO(0 0 1) following a bottom-up approach. The energy barrier for diffusing a single gold atom on the clean MgO surface was found to be 0.29 eV in full agreement with previous reports. Additionally, and as an extension to the entire energy profile related to Ostwald mechanisms, we found all of the activation energies to be below 1.05 eV in the cases investigated. An odd–even cluster trend was observed during ripening, attributed to the stability of pairing the unpaired electrons associated with the single gold atoms. Microkinetic analyses showed that Au single atoms are present on the surface of magnesia up to a temperature of 160 K. At higher temperatures, the system has enough energy for the single atom to diffuse across the surface and attach to other atoms or clusters. At temperatures akin to room temperature, the cluster undergoes ripening to form larger particles in order to achieve a more stable equilibrium.