4.73 nm compared to other samples. In continuation of the earlier report, the same group prepared the NPOMC through the same EISA strategy using amino trimethylene phosphonic acid as the dopant . The electrochemical capacitance analyses demonstrated that the gravimetric capacitance of NPOMC at 1 A g -1 in 6 M KOH solution is estimated to be 392 F g - 1 which is higher than OMC (73 F g -1 ), NOMC (217 F g -1 ) and POMC (245 F g -1 ) and 96% of capacitance retained after 5000 cycles at 20 A g -1 . Additionally, the NPOMC based symmetric cell at 1.8 V attained the energy density of 20.2 Wh Kg -1 along with 95% of retention of capacitance after 5000 cycles at 5 A g -1 in 1 M Na2SO4. The remarkable increment towards capacitance is attributed to the enriched content of heteroatoms at. % of N and 2.12 at. % of P). The NOMC formed at 800 °C achieved the maximum capacitance of 278 F g -1 at 0.2 A g -1 in 1 M H2SO4 due to the larger SBET as well as the large pore volume of 473.6 m 2 g -1 and 1.186 cm 3 g -1 along with the appreciable nitrogen doping of 7.4 at. %, respectively. Moreover, the above material was constructed as a symmetric supercapacitor and achieved the energy density of 15.8 Wh Kg -1 along with 99.6% of capacitance retained after 10000 cycles at 1 A g -1 . Juan Du et al. prepared the N, B co-doped OMC (NBOMC) via ionothermal route comprising the treatment of phenol-formaldehyde resin with 1-butyl-3-methyl imidazolium tetrafluoroborate in the high-pressure kettle at 160 °C for 1 day and the subsequent carbonization at 800 °C for 3 h in the nitrogenous environment and schematically presented in Fig. [826]. The content of boron and nitrogen in NBOMC are found to be 0.59 and 2.19 at. %, respectively. From Fig. , the area under the CV curve for NBOMC is higher than OMC due to the doping effect by boron and nitrogen atoms. Fig. depicts the plot of capacitance against current density curve of OMC and N, B-OMC revealing that the capacitance of former is found to be 143 F g -1 which is lower than the latter (272 F g -1 ) at 0.5 A g -1 in 6 M KOH solution. The amplified capacitance in N, B-OMC is attributed to its SBET of 929 m 2 g -1 which is higher than OMC (639 m 2 g -1 ). Also, the pore volume of N, B-OMC (0.96 cm 3 g -1 ) is relatively higher than OMC (0.61 cm 3 g -1 ). In addition, the N, B-OMC based symmetric cell displayed the energy density of 7.3 Wh Kg -1 along with 96% of capacitance retained from its initial value after 10000 cycles at 5 A g -1 . Xie et al. fabricated the NOMC by ESIA route by treating the phenol formaldehyde resin with pluronic F127 in presence of HCl using g-C3N4 as the dopant for 3 days followed by annealing at 700 °C for 2 h along with flow of inert gas . The NOMC obtained from the molar proportion of phenol to g-C3N4 is 1:4 exhibited the increased capacitance of 382 F g -1 at 0.5 A g -1 in 6 M KOH solution which is appreciably higher than OMC (113 F g -1 ) because of the extraordinary increased content of N (24.1 at. %). Furthermore, the optimized NOMC was developed as a symmetric supercapacitor and delivered the energy density of 29.8 Wh L -1 in 1 by etching with HF and the subsequent calcination at 400 °C for 30 minutes for 2 h in air for the elimination of template and carbonaceous impurities. The supercapacitor investigations revealed that the capacitance derived from the GCD profile of POMC at 0.2 A g -1 in 6 M KOH solution was found to be 288 F g -1 and superior to OMC (175 F g -1 ) because of the fact that the SBET as well as pore volume corresponding to POMC are 403.5 m 2 g -1 and 0.55 cm 3 g -1 and these values are significantly higher than OMC (305.2 m 2 g -1 and 0.29 cm 3 g -1 ), respectively. Also, the oxygen level of POMC (9.83 wt%) is higher than OMC . Moreover, the POMC derived symmetric supercapacitor displayed the energy density of 10 W h Kg -1 in 1 M Na2SO4 solution at 2.0 V along with 89.3% of capacitance retention after 2000 cycles. In continuation of the previous report, our group synthesized the NPOMC via CVD aided nanocasting method with SBA-15 as the template and the 1:1 weight ratio of aniline and triphenyl phosphine at 800