Tongxin Shang et al. synthesized the walnut shell derived activated carbon by carbonization at 500 °C for 1h followed by activation with potassium hydroxide in five various mass ratios of 1:1, 1:2, 1:3, 1:4, 1:5 and 1:6 at 800 °C about three hours in presence of flow of argon gas . Out of these, WSA-6 achieved the maximum specific capacitance of 330 F g -1 at 0.1 A g -1 in 6 M KOH aqueous solution by two-electrode system due to larger SBET of 3577 m 2 g -1 and higher capacitance compared to commercial activated carbon owing to the presence of oxygen functional groups in WSA-6. Furthermore, extraordinary energy density of 120 Wh Kg -1 in EMIMBF4 at the operating voltage of 4 V. In another work, picthaimani et al. obtained the porous carbon by treating the paper flower with ZnCl2 followed by microwave irradiation and finally subjected to activation with CO2 under nitrogen environment at three various temperatures (400,700 and 800 °C) about one hour . Out of these, the porous carbon obtained at 800 °C produced the maximum gravimetric capacitance of 118 F g -1 at 1 A g -1 in 1 M H2SO4 solution due to the high SBET and total pore volume of 1802 m 2 g -1 and 1.161 cm 3 g - 1 , respectively. The presence of oxygen is evident from the elemental analysis which shows 52.95 wt. % of oxygen existed in the PFA-800. Also, the 97.4% of retention of capacitance was observed for the PFA-800 electrode over 10000 cycles at 12 A g -1 . It was suggested that carbonyl groups are actively interacted with ions of the electrolyte which generate pseudocapacitance. Borghei et al. prepared the oak seeds derived activated carbon by treating the oak seeds with potassium hydroxide in mass ratio of 0.5, 1, 1.5, 2 and 2.5 followed by thermal annealing at four various temperatures (450, 550, 650 and 750 °C) along with flow of N2 gas about 3 h [866]. From Fig. , it is strongly revealed that the carbon prepared at 650