Surface Chemistry of CO on Ru(0001) under the Confinement of Graphene Cover

Abstract

In heterogeneous catalysis, graphitic carbon formed on metal often poisons metal-catalyzed reactions through physical blockage of surface active sites. In materials science, recent works show that graphene overlayers can passivate metal surfaces acting as gas-impermeable protection coatings. However, here we show using in situ surface electron microscopy and photoemission spectroscopy that CO can be readily trapped inside the two-dimensional space between the graphene overlayer and Ru(0001) surface under near-ambient conditions. The intercalated CO molecules effectively decouple the graphene overlayer from the Ru substrate. Meanwhile, the graphene cover exerts a strong confinement effect on the surface chemistry of CO on Ru(0001), showing that a high-coverage CO adlayer can be kept at the graphene/Ru interface at room temperature which desorbs intensively and completely around 390 K. This finding challenges the traditional concept of graphene films as passivation layers, indicating that the surface graphi...