Symmetric supercapacitor devices based on pristine g-C3N4 mesoporous nanosheets with exceptional stability and wide operating voltage window

Abstract

We report a facile low-cost thermal polymerization method of urea to produce 2D carbon nitride nanosheets (GCN) as confirmed via a plethora of morphological and structural characterization techniques. The GCN electrodes showed excellent electrochemical performance with a very wide operating voltage window upon their use as positive and negative poles in supercapacitor devices. The GCN exhibited high specific capacitance as positive and negative electrodes in 0.5 M H2SO4. The symmetric supercapacitor (GCN//GCN) device possesses a wide operating voltage window of 2 V, with an ultrahigh energy density of 19.33 Wh/kg and superior stability over 21,000 charge/discharge cycles. The device was assembled on graphite sheet and not on Ni foam to avoid the raised caveats on the contribution of the redox-active Ni foam to the measured capacities. These unique properties can be ascribed to the high nitrogen doping level (exceeding 12%), revealing the potential of pristine GCN as promising candidates for further investigation and development in energy conversion and storage applications.