Nitrogen/Sulfur-Codoped Carbon Materials from Chitosan for Supercapacitors

D-Methionine and chitosan have been used for fabrication of nitrogen/sulfur-codoped carbon materials by a hydrothermal process followed by carbonization at 750 degrees C for 3 h. The as-prepared carbon materials showed enhanced electrochemical performance, combining electrical double-layer capacitance with pseudocapacitance owing to the doping with sulfur and nitrogen. The specific capacitance of the obtained carbon material reached 135 F g(-1) at current density of 1 A g(-1), which is much higher than undoped chitosan (67 F g(-1)). The capacitance retention of the carbon material was almost 97.2% after 5000 cycles at current density of 1 A g(-1). With such improved electrochemical performance, the nitrogen/sulfur-codoped carbon material may have promising potential for use in energy-storage electrodes of supercapacitors.