## 3 Results and Discussion
When the current density increased, the charge/discharge time was significantly shortened. Compared to those of the Co-GPC, the similar redox peaks of the CV curves were also observed in Co-GHCP, GHCP, and GPC (Figure S2). These results could be ascribed to the introduction of the porphyrin unit with a high redox property, based on previous work [33]. However, the potentials of the redox peaks for Co-GHCP and Co-GPC were broader than those of GHCP and GPC under the same scan rate of 10 mV s\({}^{-1}\) (Figure 5c), which may be attributed to the incorporation of a metal complex with a high  
Figure 4: X-ray photoelectron spectroscopy of Co-GHCP and Co-GPC (a) survey, (b) Co 2p, (c) N 1s, respectively. redox behavior [43]. At the same current density of 1 A g\({}^{-1}\), the charge/discharge time gradually increased for the sequence of GHCP, GPC, Co-GHCP, and Co-GPC (Figure 5d), which was consistent with the above CV results. The specific capacitance of the four samples with various specific currents is shown in Figure 6a. Calculated from the discharge parts of the galvanostatic results (Figure S3), the maximum capacitance of the GHCP, GPC, Co-GHCP, and Co-GPC was able to reach 197, 244, 375, and 455 F g\({}^{-1}\), respectively, at a current density of 0.5 A g\({}^{-1}\). The best capacitance performance of the Co-GPC was attributed to its low internal resistance and the excellent pseudocapacitive behavior of the Co (II) porphyrin. Accordingly, the Co-GPC was calculated as 455, 418, 398, 350, and 315 F g\({}^{-1}\) at different specific currents of 0.5, 1, 2, 5, and 10 A g\({}^{-1}\), respectively, showing its attractive rate performance even at a high current density. To gain insight into the prominent electrocapacitance behaviors, the conductivity of the as-prepared materials was further verified via electrochemical impedance spectroscopy (EIS) analysis in 1 M KOH, with an alternating current (AC) amplitude of 5 mV (Figure 6b). The diameter of the incomplete semicircle of Co-GPC in the high frequency region was smaller than that of GHCP and GPC, indicating its lower electron transfer resistance (R\({}_{\text{ct}}\)) by formation of a Co-N-C bond within the carbon matrix. Moreover, the intercepts of the electrochemical impedance spectroscopy (EIS) curves for ohmic resistance (R\({}_{\text{S}}\)) between the current collector and the active materials indicated that the R\({}_{\text{S}}\) value of the porous carbon Co-GPC and GPC was much smaller than that of the precursors Co-GHCP and GHCP, due to the higher conductivity of the carbon material, rather than that of the hypercrosslinked polymer. The circuit fitting results are show in Figure S4 and Table S1. All the results were also in agreement with that of the specific capacitance. Figure 5: (a) Cyclic voltammograms (CV) of the Co-GPC electrodes at various scan rates; (b) The galvanostatic charge/discharge curves of the Co-GPC supercapacitor at various specific currents; (c) CV of Co-GHCP, Co-GPC, GHCP, and GPC at 10 mV s\({}^{-1}\); (d) The charge/discharge curves of the Co-GHCP, Co-GPC, GHCP, and GPC performed at the current density of 1 A g\({}^{-1}\). The cycle stability was an important issue for the supercapacitor electrode materials. The specific capacitance of the as-prepared materials was measured at a current density of 1 A g\({}^{-1}\) for 2000 cycles. As shown in Figure 6c, GHCP, GPC, Co-GHCP, and Co-GPC exhibited excellent cycling stability, and the specific capacitances of the samples increased by 6.45%, which was caused by the continuous activation of electroactive material during the charge/discharge process [30]. The energy density and power density were also important parameters that were calculated to evaluate the performance of the supercapacitors. In Figure 6d, the energy densities of Co-GPC, Co-GHCP, GPC, and GHCP were obtained at 18.43, 15.2, 9.8, and 7.9 Wh kg\({}^{-1}\) at a power density of 135 W kg\({}^{-1}\), respectively.