Nucleation of Cu-n (n=1-5) Clusters and Equilibrium Morphology of Cu Particles Supported on CeO2 Surface: A Density Functional Theory Study

In the present work, the interactions between Cu-n(n = 1-5) clusters and three low-index structural CeO2(111, 110, 100) surfaces were investigated using density functional theory calculations. The atomic Cu prefers to aggregate into large clusters on the CeO2(111) surface, whereas it is unfavorable on both CeO2(110) and CeO2(100) surfaces. Once the planar Cu4-p cluster is formed, it would convert into the three-dimensional (3D) tetrahedral Cu4-t cluster on CeO2(110) and CeO2(111) surfaces, i.e., two-dimensional to 3D transition growth is thermodynamically favorable and kinetically feasible on CeO2(110) and CeO2(111) surfaces. The effects of the ceria support structure on the morphology of the large Cu nanoparticle were examined using calculated adhesion and interfacial energies of periodic Cu(khl)/CeO2 model systems. The calculated macroscopic contact angles (theta > 100 degrees) of various model systems suggest that the supported Cu nanoparticle is in bad wetting conditions. Finally, the morphologies of large Cu nanoparticles on different CeO2 surfaces were predicted using the Wulff-Kaichew construction principle.