Formation and temperature evolution of Au nanoparticles supported on the h-BN nanomesh

Sub-monolayers of gold have been grown at room temperature on the hexagonal boron nitride (h-BN) nanomesh formed on Rh(I 11)5 and studied systematically with core level and angle-resolved valence band photoelectron spectroscopy. The results are compared with those for the Au/Rh(111) and Au/h-BN/Pt(111) interfaces. It has been found that on clean Rh(111) substrate gold starts to grow two-dimensionally (21)), while in the presence of a h-BN interlayer it forms islands from the very beginning. In the case of flat h-BN monolayer (on Pt) these islands are essentially three-dimensional (31)) and irregular in size. In contrast, on the h-BN nanomesh (on Rh) gold grows initially as regular islands (predominantly 2D), probably filling the pores of the nanomesh. In addition, the evolution of the An islands in h-BN/Rh(111) upon annealing has been investigated with core level photoemission and X-ray absorption. The annealing at temperatures between RT and 300 degrees C does not affect the 2D character of Art islands, while further increase in temperature results in formation of 3D islands. At higher temperatures (above 500 degrees C), the gold atoms diffuse through h-13N into the Rh substrate and/or desorb from the surface. However, they do not influence the chemical bond between rhodium and h-BN at any stage of annealing: the nanomesh remains intact. (c) 2008 Elsevier B.V. All rights reserved.