Because of the presence of hierarchical porous structure and the co-doping effect by both nitrogen and sulphur atoms, electroactive sites are highly pronounced that enhances the performance towards energy storage. Fascinatingly, the N, S co-doped graphene was obtained by the self-generated high gas pressure by the heat-treatment of graphene with ammonium sulphate and melamine in a sealed vacuum Cu tube at 600 °C for 3 h [657]. The content of both nitrogen and sulphur in the obtained N, S co-doped graphene are found to be 6.22 and 2.82 at. %, respectively. The obtained material has submitted the specific capacitance of 264 F g -1 at 0.5 A g -1 in 6 M KOH aqueous electrolyte by three-electrode system and achieved the good electrochemical stability with capacitance retention of 95% over 5000 cycles at 5 A g -1 in symmetric two-electrode assembly. Moreover, the gas generated during pyrolysis of the precursors created a high pressure of gas in the closed space that facilitate the incorporation of heteroatoms over the graphene skeleton. Interestingly in another study, the N, S co-doped graphene aerogel was prepared using 1-(4-mercaptobutyl)-3-methylimidazolium bromide (HS-BMIMBr) as the dopant by hydrothermal method at 200 °C for 4 h in Teflon lined autoclave . This material has achieved the specific capacitance of 182 F g -1 at 1 A g -1 in EMIMBF4 electrolyte as well as ultra-high energy density of 101 Wh kg -1 . The content of both nitrogen and sulphur in the N, S co-doped graphene aerogel from XPS analysis was found to be 2.89 and 1.31 at. %, respectively. The enhanced performance is attributed to the fact that hierarchical porous structures furnish sufficient channels for the faster migration of ions from the electrolyte, and thereby enhances the diffusion of ions.