Cu cluster deposition on ZnO (10(1)over-bar10): Morphology and growth mode predicted from molecular dynamics simulations
YT Cheng and T Liang and XW Nie and K Choudhary and SR Phillpot and A Asthagiri and SB Sinnott, SURFACE SCIENCE, 621, 109-116 (2014).
Clusters of Cu on ZnO surfaces are established catalyst systems produced by vapor deposition of Cu that consolidates into discrete clusters. Factors such as the geometry of the ZnO surface, the nature of the interface between Cu and ZnO, and the size and distribution of metal clusters strongly control the reactivity and stability of the catalyst. Here, we report on the development and use of charge-optimized many-body (COMB) potentials to model the deposition and subsequent evolution of Cu clusters on ZnO (10 (1) over bar0) using classical molecular dynamics (MD) simulations. The simulations predict that the deposited Cu spreads to form two-dimensional (2D) structures until the coverage is above 0.4 monolayers (ML). Thereafter, the 2D structures grow thicker with increasing Cu coverage and finally form three-dimensional (3D) clusters. The predictions are compared to published experimental data and help to elucidate aspects of the growth that are currently the subject of controversy in the literature. In addition, the influence of such factors as incident cluster deposition energy, ZnO surface temperature, and different supports on the surface morphology of the Cu clusters are examined. The results are expected to provide useful guidance for the improved production of dispersed Cu clusters on ZnO surfaces. (C) 2013 Elsevier B.V. All rights reserved.
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