PNNL

Abstract

The thermal behavior of various amounts of palladium deposited onto graphene/Ru(0001) at room temperature was investigated by x-ray photoelectron spectroscopy (XPS) and infrared reflection absorption spectroscopy (IRAS) of adsorbed CO. IRAS spectra of adsorbed CO on palladium deposited onto the graphene layer reveal the formation of defect-rich, highly-stepped and/or nanoparticle-typed palladium clusters. Annealing to temperatures below ~900 K, palladium clusters mainly experience agglomeration on the graphene layer, but at higher temperatures intercalation of palladium between the graphene layer and Ru substrate takes place. Eventually, palladium completely desorbs and the graphene layer dissolves into the ruthenium substrate at 1400 K. Even though the annealing induces the intercalation and desorption of palladium, the topmost graphene layer stays intact without any physical damage at and below 1300 K. We gratefully acknowledge the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division for the support of this work. The research described in this article was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle Memorial Institute under contract number DE-AC05-76RL01830. CWY also acknowledges the support of this work by Sungshin Women’s University Research Grant of 2014.