Olmos-Asar Jimena A, Vesselli Erik, Baldereschi Alfonso, Peressi Maria
Department of Physics, University of Trieste, Strada Costiera 11, 34151 Trieste, Italy.
Phys Chem Chem Phys. 2014 Nov 14;16(42):23134-42. doi: 10.1039/c4cp03271c.
The mechanisms of seeding and nucleation of Cu nanoclusters onto an ultrathin alumina template supported on Ni3Al(111) has been investigated by means of ab initio calculations. Single Cu ad-atom diffusion on the oxide film is effective at room temperature, allowing preferential occupation of the defective sites of the so-called "dot" structure, where the adsorption is much stronger than in the "network" or any other surface site of the oxide. After the adsorption of the first Cu atom, further nucleation at the "dot" sites proceeds with the formation of multi-atomic seeds (with up to 6 atoms contained in the defect) that offer stiff anchoring for larger clusters. The whole process is thermodynamically favoured. We therefore clearly confirm and rationalize some experimental evidence showing that the ultrathin Al2O3/Ni3Al(111) is an efficient template for the growth of highly ordered arrays of small Cu nanoparticles.
通过从头算计算研究了铜纳米团簇在Ni3Al(111)负载的超薄氧化铝模板上的成核和播种机制。单个铜吸附原子在室温下在氧化膜上的扩散是有效的，这使得所谓“点”结构的缺陷位点能够优先被占据，在该位点的吸附比氧化膜的“网络”或任何其他表面位点要强得多。在第一个铜原子吸附之后，“点”位点上的进一步成核过程伴随着多原子种子（缺陷中最多包含6个原子）的形成而进行，这些种子为更大的团簇提供了牢固的锚定。整个过程在热力学上是有利的。因此，我们明确证实并合理解释了一些实验证据，这些证据表明超薄Al2O3/Ni3Al(111)是生长高度有序的小铜纳米颗粒阵列的有效模板。
