Tuning the nature of nitrogen atoms in N-containing reduced graphene oxide

Physical and chemical properties of graphene can be tailored by nitrogen doping. As a consequence of the continuous race to achieve the highest possible amount of doping there is a growing tendency to assume that all N species are incorporated within the graphene lattice (doping). Here we show that this is not always the case and employ several complementary techniques that allow a proper assessment of the type of nitrogen present. The nature of the nitrogen atoms has been tuned by ammonolysis of graphene oxide in the range of 100 °C–800 °C. This allows us to expand the capabilities of the synthetic approach to afford not only N-doping (at high temperature) but also to introduce amine and amide moieties at 100 °C; the latter presenting a much higher dispersability in aqueous media than graphene oxide. Interestingly, the sample with the highest amount of nitrogen (14.7 wt. %) cannot be referred to as N-doped graphene since it also contains N-bearing aliphatic moieties.We acknowledge financial support from MINECO (grants ACI2009-0861 and MAT2014-53500-R, Spain) and Department of Science and Technology (DST, India). This work has been carried out under the Materials Science PhD program of the Universitat Autònoma de Barcelona (UAB). The XPS data were acquired at the Laboratorio de Microscopías Avanzadas (LMA) - Instituto de Nanociencia de Aragón (INA), and EA in the Centres Científics i Tecnològics - Universitat de Barcelona, both in Spain.Peer reviewe