▎ 摘　　要

We have studied the interaction of CO with epitaxial graphene on Pt(111) and Ru(0001) by means of high-resolution electron energy loss spectroscopy measurements. Our experiments unambiguously demonstrate that in ultra-high vacuum conditions CO does not intercalate underneath the graphene monolayer supported on Pt(111) and Ru(0001). For submonolayer coverages of graphene on Pt(111), CO adsorption occurs only in Pt on-top sites while bridge sites, usually populated on the clean Pt(111) surface, are inhibited. Instead, we find that epitaxial graphene is rather reactive toward water molecules. (C) 2013 Elsevier Ltd. All rights reserved.