Interaction of gold clusters with graphene and graphene layer over Ni (111) surface: A density functional study

Heterogeneous catalysis on support stabilized metal clusters has shown significant progress in the past decade. In order to unravel the effect of neutral support on the growth motif of small clusters, here we report structural and electronic properties of Au-n (n = 2, 6, and 8) clusters deposited on Ni(1 1 1) supported graphene sheet using the spin-polarized version of the plane wave based pseudo-potential method. In general, the trend in the growth pattern shows that all deposited Au, clusters favor planar configurations, similar to that in the isolated case. More importantly, the binding energy of the Au-n clusters on graphene increases with the Ni support, which is an important outcome as it can be realized that the Ni (1 1 1) support indeed helps in stabilizing the Au-n clusters on the graphene, avoiding them from aggregating, a common problem in heterogeneous catalysis. A finite amount of overall charge transfer from the substrate to the deposited cluster was observed with a charge accumulation of 0.44e in case of Au-8 which can play a significant role for enhancing its catalytic performance. From the density of states it was revealed that the energy states form Au-8 cluster contributed to the fermi energy level of the Au-8 - Ni(1 1 1) - graphene, suggesting a possible reactivity of this cluster.