Among the existence of variety of elements in the periodic table, N-doping is the preferred for the doping due to which both N and C are almost identical in size. Besides, the more polarisation is generated in C-N bond and adsorption of electrolyte ion is favoured owing to the fact that the electronegativity of nitrogen (3.04) is relatively higher than carbon [160]. Normally, the n-type semiconducting behaviour is incorporated after the doping of nitrogen into the graphene skeleton. There are six possible kinds of nitrogen doped in the graphene lattice as clearly observed from Fig. . They are pyrrolic, pyridinic and graphitic/quaternary N, pyridinic-N-oxide, amine and amides. In general, nitrogen containing compounds which contains localised charge such as amines, amides and its protonated form are observed at low temperature which are unstable whereas the nitrogen bearing compounds which has delocalized charge such as pyrrole, pyridine are obtained at higher temperature and beneficial for the electrochemical performance . Among the different types of doped nitrogen, both pyridinic and pyrrolic nitrogen are the one which present at the edges of graphene but graphitic nitrogen is the one which exist in the basal plane. Pyridinic nitrogen is the one which contributes one electron from the p-orbital to the aromatic π-system in a hexagonal six-membered ring while pyrrolic nitrogen is the one which contributes two electrons from the p-orbital to the aromatic π-system in a pentagonal five-membered ring as obviously displayed in Fig. . The unshared pair of electrons in the pyridinic structure is in the sp 2 hybrid orbital which is distributed outside the ring whereas the lone pair of electrons in the pyrrolic structure are in the p-orbital which is delocalized inside the ring .