Nitrogen implantation into graphene oxide and reduced graphene oxides using radio frequency plasma treatment in microscale

Solvent-free radiofrequency (RF) nitrogen plasma treatment was applied to incorporate nitrogen atoms in relatively high concentration. Graphene oxide (GO) and two reduced GOs of different O-content were used as target substrates to reveal the influence of the functional groups decorating the graphene lattice on the quantity and quality of nitrogen incorporation. Despite the relatively high oxygen content of the samples no N-O bonds develop but three kinds of different N-C bonds of very similar concentration are formed. Reduction of the GO removed the O-groups but did not heal the vacancies where N doping may occur. After two days the implanted N content drops, the N1 state (sp(2) N in pyridine ring, C-N-C) showing the least stability.