Complex growth of NanoAu on BN nanomeshes supported by Ru(0001)

Abstract

Detailed scanning tunneling microscopy measurements reveal the complex interaction of Au with a h-BN nanomesh on Ru(0001). The h-BN overlayer on Ru(0001) consists essentially of a hexagonal lattice of 2 nm wide pores with an in-plane lattice constant of 3.25 nm. The h-BN nanomesh can be regarded as a highly regular network of trapping sites in which Au particles have shown to condense exclusively with a narrow size distribution, thus forming well-suited Au model catalysts. At higher Au coverages two-dimensional metal islands are formed on as well as under the h-BN nanomesh depending on the deposition and annealing procedure. Au atoms can penetrate through defects in the h-BN nanomesh (most notably at step edges) in between the h-BN nanomesh and the Ru(0001) substrate at higher temperatures (activates process). Multi layers of Au form a continuous film between Ru(0001) and h-BN after annealing to 1050 K, thereby lifting the nanostructuring of the h-BN layer due to the weak interaction of h-BN with Au.