[509]. The proposed cause is due to the fact that the pre-treatment of melamine with H2SO4 leading to a various condensation process during which the sublimation of melamine was distinctly prevented. Dong and Zhang reported the preparation of g-C3N4 from HCl-protonated melamine and the obtained material comprises a thin porous platelet-like structure, suggesting Hence it has been generalised that the g-C3N4 was prepared by the thermal polymerisation of various precursors such as melamine, urea and thiourea in the temperature ranges such from 500 to 600 °C. The g-C3N4 prepared from the variety of precursors reported in the literature is tabulated in Table . The advantages as well as limitations of various synthetic strategies are pictorially presented in Fig. . reported that the GO was also reduced with ammonia water under hydrothermal treatment in a teflon lined autoclave at 180 °C for 10 h to produce the amine functionalized graphene which shown the specific capacitance of 217.8 F g -1 at 0.4 A g -1 in 0.5 M H2SO4 solution as the electrolyte and considerably greater than RGO (135 F g -1 ) . The highest value is attributed to the presence of amine functionalities which can access its unshared pair of electrons to H + from H2SO4 electrolyte. Moreover, the SBET and the pore volume of amine functionalized graphene were found to be 346 m 2 g -1 and pore volume of 2.88 cm 3 g -1 , both of which are correspondingly greater than 272 m 2 g -1 and 1.77 cm The nitrogen content as well as the specific capacitance of the GHTC-a were found to be 2.2 at% and 300 F g -1 at 0.1 A g -1 in 6 M KOH solution by two-electrode system which is relatively larger than the sample prepared without graphene (HTC-a; 250 F g -1 ), respectively.