Hierarchical porous carbon sheets derived on a MgO template for high-performance supercapacitor applications

Carbon-based supercapacitors have attracted considerable academic and practical interest due to their advantages of low cost, high power density, and superior durability. Herein, we report the facile synthesis of hierarchical porous carbon sheets (HPCSs) featuring a high specific surface area (2788 m² g^-1), derived from pyrrole through a combination of MgO template carbonization and KOH activation. The hierarchical pores with the co-existence of micropores and mesopores were obtained in the HPCSs. Benefiting from the high surface area, well-balanced pore size distribution as well as high conductivity, the prepared HPCSs exhibited a high gravimetric specific capacitance of 226.4 F g^-1 at a scan rate of 1 mV s^-1 in the electrolyte of 1 M H₂SO₄ in the two-electrode configuration. Moreover, the excellent electrochemical long-cycle stability has been demonstrated by 10 000 cycles of rapid charging-discharging at 10 A g^-1 with a capacitance retention of 97.3%. The electrochemical performance clearly indicates the promising potential of using HPCSs as electrode materials for supercapacitors.