Realization of nickel doped carbon enriched graphitic carbon nitride for diffusion controlled charge storage

Abstract

Here in this communication we report synthesis of Nickel doped carbon enriched graphitic carbon nitride for supercapacitor applications. Although the FTIR spectra of carbon enriched gC₃N₄ indicates the destruction of out of plane heptazine ring but simultaneously shows the preservation of tri – s - triazine structure of gC₃N₄. There is a blue shift in absorption peak resulting in the widening of the band gap by doping the carbon enriched gC₃N₄ with nickel. In XRD spectrum the peak shift towards lower angle with decrease in the intensity is observed indicating widening in in-plane stacking of s- triazine rings. The cyclic voltammetry studies show increase in the specific capacitance from 91.5F/g for gC₃N₄ to as high as 226F/g @ 10 mV/s for nickel doped carbon enriched gC₃N₄ (NiCgC₃N₄). This increase in the charge storage can be attributed to the increase in the diffusion of electrons aided by doping of carbon enriched graphitic carbon nitride by nickel as suggested by Randles Sevick calculation. The Lindstrom & Dunn's methods points out that the charge storage is by faradaic diffusion controlled processes at the electrode and electrolyte interface. Furthermore NiCgC₃N₄ electrode exhibits a good stability of 79.5 % up to 4000 cycles. The as synthesized electrode material NiCgC₃N₄ basically shows the psuedocapacitive nature. The asymmetric two electrode device showed a specific capacitance of 119F/g @ 1 A/g. A maximum energy density of 214 Wh/Kg with power density of 1800 W/Kg is achieved for 1 A/g current density. Overall the synthesized NiCgC₃N₄ has shown good diffusion controlled charge storage material qualities.