Using O2 in air to modify N-doped carbon nanosheets for the generation of high-performance supercapacitor

Abstract The doping of functional heteroatoms into carbon materials with ions-accessible surfaces could address the problem of low energy storage ability of carbon electrodes. In this study, porous carbon nanosheets with high oxygen and nitrogen content in the lattice have been fabricated by doping oxygen into N-doped carbon nanosheets. After a series of operations involving templating synthesis, oxidation, and carbonization, N,O-functionalized porous carbon nanosheets was fabricated using MgO as template, polyacrylonitrile (PACN) as nitrogen source and O2 in air as oxygen source. The resulted amorphous PACN-MgO-700 is in the form of porous nanosheets, exhibiting specific surface area of 555 m2/g and pore volume of 0.43 cm3/g. With high N (8.7 atom%) and O (9.7 atom%) content in the lattice, PACN-MgO-700 achieves high specific capacitance of 189.6 F/g at 1.0 A/g, acceptable energy density of 26.3 Wh/kg at power density of 505.9 W/kg, as well as extraordinary cycling stability at high current density of 5.0 A/g (98% capacitance retention after 20 000 charge/discharge cycles). This work provides a promising strategy for functionality adjustment and morphology control of oxygen-containing carbon materials.