Zhang et al. reported a facile approach to prepare nitrogen-doped hierarchical porous carbon by using sodium acetate as the activation agent, phenolic resin as the carbon precursor, and hexamethylenetetramine as nitrogen source . This work was attempted with an aim to achieve the direct carbonization of nitrogen-containing precursors by avoiding KOH and NaOH activators, which may cause serious corrosion. The carbon materials were synthesized at different annealing temperatures (500, 600, 700, 800, and 900 ˚C), and were designated as PHS-T, where T refers to the annealing temperature. The SBET of PHS-T samples was determined from BET analysis. PHS-500, PHS-600, PHS-700, PHS-800, and PHS-900 showed the SBET of 171, 327, 827, 1414, and 1591 m 2 g -1 , respectively. The SBET was found to be significantly improved with increasing the annealing temperature with the maximum value of 1591 m 2 g -1 with a pore volume of 0.87 cm 3 g -1 was obtained for PHS-900. The XPS studies showed the presence of N, and O heteroatoms, which were negatively correlated with the annealing temperature. For instance, the PHS-600, PHS-700, PHS-800, and PHS-900 showed the presence of N/O contents of respectively. The electrochemical performances of PHSs were tested using a three-electrode system in 7 M KOH, and delivered the specific capacitances of 286, 352, 309, and 290 F g -1 for PHS-600, PHS-700, PHS-800, and PHS-900 electrodes, respectively at 0.5 A g -1 . The PHS-900 electrode delivered the low specific capacitance of 290 F g -1 , even though the SBET of PHS- 900 was maximum (1597 m 2 g -1 ), which might be due to the low residual nitrogen content as evident from XPS analysis. Further, the PHS-700 electrode showed the long-term stability in a two-electrode system with a capacitance retention of 95.3% after 10000 cycles. The best supercapacitive performances of PHS-700 are attributed to the optimum balance between high nitrogen content , and relatively large SBET (827 m 2 g -1 ). Song Yan et al. reported the synthesis of nitrogen-doped porous carbons (LS-NCs) from biomass of waste lotus stems for high-performance supercapacitors . The lotus stems were mixed with urea, carbonized under N2 atmosphere, and chemically activated by KOH under different temperatures (600, 700, 800, and 900 ˚C) to obtain LS-NC-600, LS-NC-700, LS-NC-800, and LS-NC-900, respectively. The XPS analysis displayed the peaks corresponding to pyridine nitrogen (N-6), pyrrolic/pyridinic nitrogen (N-5), and oxidized nitrogen (N-X). The total nitrogen contents were inversely proportional to the activation temperature, and indicated that the higher temperature will result in more loss of nitrogen atoms during activation. In LS-NC-900, LS-NC-800, LS-NC-700, and LS-NC-600, the N-6 percentage was increased from 39.1% to 79.1%, where N-5 percentage was decreased from 43.4% to 15.6%, as a whole, the N-6, and N-5 contents accounted for 94.7% of the total nitrogen, and significantly contributed to conductivity. The SBET of LS-NCs were initially increased, and then decreased with increasing activation temperature. LS-NC-600, LS-NC-700, LS-NC-800, and LS-NC-900 samples showed the SBET of 1322, 2013, 2221, and 1986 cm 2 g -1 . These results suggested the collapse of structure upon excessive temperature, and enhancement of KOH activation. The electrochemical measurements were carried out in three-electrode system using 6 M KOH, and LS-NC electrode showed the highest capacitance value of 360.5 F g -1 at 0.5 A g -1 , versus LS-NC-700 (269. 1 F g -1 ), LS-NC-800 (243. 3 F g -1 ), and LS-NC-900 (195. 1 F g -1 ), respectively.