Effects of nitrogen doping on supercapacitor performance of a mesoporous carbon electrode produced by a hydrothermal soft-templating process

Abstract

A soft-templating hydrothermal approach is developed for synthesizing nitrogen (N)-doped mesoporous carbon. D-Fructose and dicyandiamide (DCDA) are used as the starting materials for carbon and nitrogen precursors, respectively, and Pluronic® F127 as the soft template. N-doped mesoporous carbon shows a significant improvement in electrical conductivity and specific capacitance (212 F g⁻¹ under 1 mV s⁻¹ scan rate), compared with the un-doped carbon derived from the same process. A tunable N-doping level (from 4.5 to 14.5 wt%) and specific surface area (ranging from 375 to 730 m² g⁻¹) are realized by changing the DCDA to D-Fructose weight ratio. The three factors that affect the electrochemical performance, including the specific surface area, electrical conductivity and pseudocapacitance, have been systematically studied. Doping of 6.0 wt% N into carbon appears to be the optimum level for obtaining high electrochemical capacitance. In this work, the effects of N-doping and the interactions among the three factors affecting the capacitance are clarified, shedding light on the future work on the rational design of electrode materials for improved electrochemical performance.