N-doped porous carbon sheets derived from ZIF-8: Preparation and their electrochemical capacitive properties

Taking ZnO nanorods as a template, N-doped and porous carbon sheets (NPCS) were obtained by high-temperature carbonization and KOH activation of ZIF-8@ZnO hybrids. The morphology, structure and elemental composition of the as-obtained NPCS were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and N-2 adsorption analyzer. The NPCS showed a large specific surface area (1190 m(2) g(-1)), high specific capacitance of 290 F g(-1) at current density of 1 A g(-1), and superior charge-discharge cycle stability (the capacitance retains 94% after 10,000 cycles at a high current density of 20 A g(-1)). Furthermore, the NPCS//NPCS two-electrode symmetric supercapacitor also showed high energy density and power density, and excellent rate performance of 81.9% capacitance retention when the current density was increased from 0.5 to 50 A g(-1). These suggested the great potential applications of NPCS in high-performance electrochemical supercapacitors.