Synthesis of nitrogen-doped graphene via simple microwave-hydrothermal process

•Nitrogen-doped graphene was successfully synthesized via microwave-hydrothermal method.•The processing time is significantly reduced compared with previously proposed methods.•Oxygen concentration is decreased and nitrogen doping concentration is increased with microwave treatment time.•Concentration of pyridinic-N atoms in graphene layers is increased with microwave treatment time.

In this letter we demonstrate successful application of the microwave-hydrothermal method to the synthesis of nitrogen-doped graphene. The processing time is significantly reduced compared to previously proposed methods as a result of rapid heating by microwave radiation involving agitation of polar molecules and oscillation of ions. Nitrogen-doped graphene has been synthesized from graphene oxide (GO) via microwave-hydrothermal process in ammonia solution. We investigated the chemical composition and bonding configuration of inserted nitrogen atoms in graphene layers synthesized in different microwave treatment time. From the analysis of chemical composition, we found that nitrogen doping is achieved simultaneously with the oxygen reduction process. With increasing synthesis time, nitrogen doping concentration increased to 6.13 at% and oxygen composition rapidly decreased due to oxygen reduction. Moreover, we also show enhanced formation of pyridinic-N atom.