Nitrogen-doping graphene at ambient conditions with N2-DBD-plasma and the role of neutral species

We doped nitrogen into monolayer graphene using reactive nitrogen species from a dielectric barrier discharge (DBD). After 30 s of treatment, the graphene monolayer had a moderate degree of damage (I_D/I_G = 1.2) and an increase in the N-atom (pyrrolic) and O-atom (mixed) content. During long treatment times (20 min), the treated area increased radially and the graphene was destroyed. Overall, the N-atom content increased with increasing operating voltage of the DBD source. When the graphene was treated with only neutral reactive nitrogen species, the N-atom content and type remained unchanged. Therefore, we hypothesize that the primary reactive species resulting in pyrrolic N-doping from the DBD are neutrals such as N(⁴S) and possibly N(²P).