Modulation of Surface Chemistry of CO on Ni(111) by Surface Graphene and Carbidic Carbon

Nickel carbide and graphene overlayers were grown on Ni(111), which were in situ monitored by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and low energy electron microscopy. CO adsorption and desorption on the formed carbon-modified Ni(111) surfaces were further investigated by NAP-XPS. We found that the carbidic carbon weakens CO adsorption on Ni, resulting in quick CO desorption around room temperature. A full graphene layer on Ni(111) blocks CO adsorption in 10 –6 Torr CO, while CO intercalates the graphene overlayers in 0.1 Torr CO at room temperature. On the graphene/CO/Ni(111) surface, the major part of intercalated CO molecules desorbs extensively around 90 °C from the graphene/Ni interface and the remaining part gets trapped under the graphene even at 200 °C. These results suggest that the surface reactivity of a metal catalyst can be strongly modulated by surface carbon structures.