Mechanism of CO Intercalation Through the graphene/Ni(111) Interface and Effect of Doping
Molecules intercalate at the Graphene/Metal interface even though defect-free graphene is impermeable to any atomic and molecular species in the gas and liquid phase, except hydrogen. The mechanism of molecular intercalation is still a big open question. In this letter, by means of a combined experimental (STM, XPS and LEED) and theoretical (DFT) study, we present a proof of how CO molecules succeed in permeating the graphene layer and get into the confined zone between graphene and the Ni(111) surface. The presence of N-dopants in the graphene layer is found to highly facilitate the permeation process, reducing the CO threshold pressure by more than an order of magnitude, through the stabilization of multi-atomic vacancy defects that are the open doors to the bidimensional nanospace, with crucial implications for the catalysis under cover and for the graphene electrochemistry.