###### Abstract
[35] studied a chemical exfoliation of GO to produce reduced graphene oxide with a selective number of layers based on different starting materials such as pyrolytic graphite, natural flake graphite, Kish graphite, flake graphite powder, and artificial graphite. They reported the effect of the lateral size and crystallinity of these starting graphite materials on the number of graphene layers presented in the obtained graphenic material. They found that graphite samples with a small lateral size and low crystallinity produce a higher proportion of single layer graphene. [PERSON] et al. [34] obtained NrGO through the thermal annealing of GO in NH\({}_{3}\) sweeping temperatures between 300 and 1100 \({}^{\circ}\)C. Annealing at 500 \({}^{\circ}\)C afforded the highest N-doping level of \(\sim\)5%, showing the strong influence of the temperature on the nitrogen content of the obtained materials. They claim that the N-doping degree depends on the amount of oxygen functional groups of graphene as they are responsible for the formation of C\(-\)N bonds. The higher the annealing temperature is, the lower the content of oxygen, leading to a lower reactivity between the graphene layer and NH\({}_{3}\). The production of NrGO based on the annealing of GO in the presence of melamine at high temperature (700-1000 \({}^{\circ}\)C) has been reported by [PERSON] et al. [32]. They noted that nitrogen content depends on the mass ratio between GO and melamine as well as on the temperature, reaching values of 10.1 at % using a 1:5 ratio of GO to melamine at 700 \({}^{\circ}\)C. A similar approach was used by [PERSON] et al. [33] working with urea and GO as precursor materials of NrGO. They used the ratio of GO to urea as a way to control the amount of nitrogen inserted and the surface area values obtained. Nonetheless, neither [PERSON] et al. [34] nor [PERSON] et al. [33] reported a systematic study of the synthesis conditions to optimize NrGO properties. [PERSON]'s group [25] analyzed the effect of the experimental conditions of the thermal transformation of GO onto rGO, finding that the treatment temperature strongly affects the type and amount of functional groups obtained. Following this line of research, they proposed that the temperature of the initial flash thermal treatment allows the control of the surface area obtained [36]. However, the surface area values achieved were lower than 500 m\({}^{2}\)g\({}^{-1}\). [PERSON] et al. [37] proposed a vacuum-promoted thermal exfoliation method for different samples of GO, which were obtained from natural flake graphites with particle sizes ranging from 100 to 5000 mesh. Nevertheless, neither the morphology nor the structures of different graphenic samples were affected by the parent graphite particle size. The surface areasobserved were around 490 m\({}^{2}\)g\({}^{-1}\) and the C/O ratio determined by XPS analysis revealed that all the samples had almost the same oxygen content. Thus, the vacuum-promoted exfoliation method minimizes the differences originated from the raw graphite particle size. The effect of the raw graphite size on the rGO properties has been also described by [PERSON] et al. (2018). They prepared rGO by the rapid heating of dry GO using three graphite particle sizes obtained from grinding a large graphite sample. An increase in the surface area was observed as the particle size of the samples was reduced, reaching a value of 739 m\({}^{2}\)g\({}^{-1}\) in their best sample. This improvement was explained as being due to the better oxidation degree achieved with the decrease of the graphite particle size, which also favors a better exfoliation of the GO. On the other hand, a previous study of our group ([PERSON] et al., 2018) reported the synthesis of NrGO from GO obtained from three different graphite particle sizes. We found that the quantity of nitrogen and the surface properties obtained were dependent on the particle size of the graphite used. However, the surface areas obtained were not optimized enough.