Oxide-mediated nitrogen doping of CVD graphene and their subsequent thermal stability.

Heteroatom doping of graphene is a promising approach for tailoring its chemical and electronic properties - a prerequisite for many applications such as sensing, catalysis, and energy storage. Doping chemical vapour deposition (CVD) graphene with nitrogen during growth (in-situ doping) is a common strategy, but it produces a distribution of inequivalent dopant sites and requires substantial modifications to the CVD growth process. In this study, we demonstrate a novel and simple oxide-mediated approach to introduce nitrogen dopants into pre-existing CVD graphene (ex-situ doping) which achieves comparable doping densities to in-situ doping methodologies. Furthermore, we demonstrate that thermal annealing of N-doped graphene can selectively remove pyridinic, retaining graphitic and pyrrolic nitrogen dopants, offering an attractive route to further modify graphene functionality. The methodologies we present are simple and scalable to precisely tailor graphene properties without the need to alter CVD growth protocols.