Interestingly, Ma et al. reported the fabrication of nitrogen and sulphur co-doped graphene-enriched carbon foam bearing hierarchical porous nature (N, S-GHPCF) by a onepot sol-gel method accompanied by a one-step high-temperature treatment, in which the carbonization, activation, heteroatom doping, and thermal reduction of GOs occurred in a concerted manner using thiourea as the dopant . The content of nitrogen and sulphur in the N, S-GHPCF was found to be 6.67 and 2.08 at. %, respectively. Also, it has acquired the high specific capacitance of 405 F g -1 at 1 A g -1 in 6 M KOH aqueous solution as the electrolyte with superior rate performance of 295 F g -1 at 100 A g -1 along with outstanding electrochemical stability of 98.8% retention of capacitance over 10000 cycles. The existence of 3 D architecture along with porous structure and the availability of heteroatoms not only enrich the wettability but also facilitate the additional pseudocapacitance. Moreover, 3D porous architecture generated the excellent interface between electrode and electrolyte that could create the sufficient electroactive sites which is reliable for ion accessibility leading to the improved capacitive behaviour. Wu et al. synthesized the N, S co-doped graphene by hydrothermal treatment of GO with methionine at 160 °C for 4 h by varying the mass ratios of GO and methionine and employed as a binder-free electrode . Among the three various samples, the optimised material in which the mass ratio of methionine and GO is 0.5:1 has delivered the specific capacitance of 431 F g -1 at 0.5 A g -1 in 6 M KOH aqueous solution. The doping content of nitrogen and sulphur in the optimised sample is estimated to be 1.5 and 0.3 at. %, respectively. The main cause for the augmented behavior towards energy storage is not only the high SBET of 260 m 2 g -1 but also the pseudocapacitance provided by doped nitrogen and sulphur. Deng et al. prepared the N, S co-doped graphene by solvothermal method using thiourea as the source and delivered the specific capacitance of 176.5 F g -1 at 1 A g -1 along with 95% capacitance retention after 10000 cycles [661]. Zhu et al. investigated the electrochemical supercapacitor performance of 3D nitrogen/sulfur-co-doped porous graphene hydrogels which were produced by reduction and self-assembly process of GO with thiourea by varying the pH value . The optimized material without binder which contained 2.12 at. % of nitrogen and 0.52 at. % of sulphur has reached the specific capacitance of 259 F g -1 and retained 96% of its initial capacitance over 10000 cycles in 2 M KOH solution. This is because of the fact that when the pH value increases then the repulsive forces between the sheets of graphene also enhances that giving rise to the highly porous network which improves the ionic accessibility towards the surface of the electrode. Moreover, the same material was assembled as a symmetric supercapacitor and achieved an energy density of 6.08 Wh Kg -1 . In another report, the Domga et al. obtained the N, S co-doped graphene by the one-pot microwave method at 800 W for 5 minutes . The synthesis was performed with different weight ratios of thiourea and GO. The synthesized sample has got the doping level of 14.9% and 4.3% of nitrogen and sulfur, respectively. The optimized ratio has achieved the specific capacitance of 460 F g -1 1 A g -1 in 1 M H2SO4 electrolyte. Also, a high energy density of 32 and 59 Wh kg -1 were attained in EMIMBF4 and hydroquinone based redox additive electrolyte, respectively. From this it is apparently inferred that not only the synthesis method but also the quantity of precursor also played a significant role in the performance of supercapacitors.