Covalent modification of graphene by hyperthermal collisions
G. Dubey, R. Urcuyo, S. Abb, G. Rinke, M. Burghard, S. Rauschenbach, and K. Kern
Chemical functionalization of graphene is achieved by hyperthermal reaction with azopyridine molecular ions. The one-step, room temperature process takes place in high vacuum using an electrospray ion beam deposition (ES-IBD) setup. For ion surface collisions exceeding a threshold kinetic energy of 165 eV, molecular cation beams of 4,4’-azobis(pyridine) covalently attach to chemical vapor deposited (CVD) graphene. A covalent high functionalization degree of 3% of the carbon atoms of graphene is reached after 3-5 hours of ion exposure of 2·1014 azopyridinium/cm2 of which 50% bind covalently. This facile approach for the controlled modification of graphene extends the scope of candidate species that would not otherwise react via existing conventional methods.