N, O self-codoped hierarchical porous carbon from chitosan for supercapacitor electrode active materials

The oxygen and nitrogen self-codoped activated carbon nanosheets are facilely prepared from chitosan by using ZnCl2. The optimal carbon possesses a significantly increased specific surface area (SBET = 1679 m2 g− 1) and richer porosity (Vp = 0.792 cm3 g− 1) in comparison with the pristine carbon prepared without using ZnCl2 (Vp = 0.035 cm3 g− 1, SBET = 80 m2 g− 1). The well-developed hierarchical porous structure and high heteroatom contents (N 7.35 at%, O 8.96 at%) endow the optimal carbon superior capacitive performance. It delivers a specific capacitance of 287.94 F g− 1 at 1.0 A g− 1 in the three-electrode supercapacitors. Moreover, the optimal carbon-based symmetric supercapacitor achieves an energy density of 28.74 Wh kg− 1 when the power density is 399.92 W kg− 1, and demonstrates satisfactory cycling stability. Our work provides an effective way for fabricating heteroatom self-doped porous carbon materials for advanced electrochemical energy storage devices.