Density Functional Theory Study of Ni Clusters Supported on the ZrO2(111) Surface

The nickel/zirconia (Ni/ZrO2) interface plays a key role in the performance of the anode of solid oxide fuel cells (SOFC) and it is therefore important to understand the interaction between nickel nanoparticles and the ZrO2 surface. Here, we have described the interaction of five Ni-n (n = 1-5) clusters with the (111) surface of cubic zirconia, c-ZrO2(111), using spin polarized density functional theory (DFT) calculations with inclusion of long-range dispersion forces. We have systematically evaluated the geometric and electronic structure of different cluster configurations and sizes and shown how the clusters interact with the oxygen and zirconium surface atoms. The cluster-surface interaction is characterized by a charge transfer from the Ni clusters to the surface. From calculations of the hopping rate and clustering energies, we have demonstrated that Ni atoms prefer to aggregate rather than wet the surface and we would therefore suggest that modifications in the synthesis could be needed to modify the coalescence of the supported metal particles of this catalytic system.