Covalent modification of graphene by hyperthermal collisions

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.