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A new solvent free protocol is presented to introduce amide and amine functionalities (N-aliphatic groups) onto graphene oxide in an energy efficient manner. Nitrogen contents of 3.6 wt% are obtained in only 5 minutes at room temperature by using ammonia gas as the nitrogen source for the ammonolysis of graphene oxide. [ABSTRACT FROM AUTHOR]

Nitrogen-doped reduced graphene oxide (Ndoped RGO) samples with a high level of doping, up to 13 wt.%, have been prepared by annealing graphene oxide under a flow of pure ammonia. The presence of nitrogen within the structure of RGO induces a remarkable increase in the thermal stability against oxidation by air. The thermal stability is closely related with the temperature of synthesis and the nitrogen content. The combustion reaction of nitrogen in different coordination environments (pyridinic, pyrrolic, and graphitic) is analyzed against a graphene fragment (undoped) from a thermodynamic point of view. In agreement with the experimental observations, the combustion of undoped graphene turns out to be more spontaneous than when nitrogen atoms are present. [ABSTRACT FROM AUTHOR]

The thermodynamic stability of a series of nitrogen - doped reduced graphene oxides prepared by ammonolysis of graphene oxide has been investigated by high temperature oxidation calorimetry. In terms of enthalpy and depending on the concentration of nitrogen, the nitrogen - doped reduced graphene oxides can be up to 73 kJ·mol−1 more stable than graphite plus nitrogen. There is a linear relationship between the nitrogen content and the formation enthalpy, which indicates a decrease in stability with increasing nitrogen content. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]