Coal derived graphene as an efficient supercapacitor electrode material

• Published in: Chemical physics 2020-02, Vol.530, p.110607, Article 110607
• Main Authors: Singh, Arvind, Ojha, Animesh K.
• Format: Article
• Language: English
• Subjects: Coal; Electrode materials; Graphene; Supercapacitors
• ISSN: 0301-0104
• DOI: 10.1016/j.chemphys.2019.110607

Micro-sized graphene sheets are synthesized using coal as a starting material. A maximum value of specific capacitance of 277 F/g at scan rate of 5 mV/s is found in 1M Na2SO4. It shows long cycle stability and the low value of RCT indicates fast ion/electron transport and rapid adsorption-desorption rates of ions in the electrode. [Display omitted] •Micro-sized graphene sheets were synthesized using coal as a starting material.•It shows excitation independent photoluminescence emission.•A maximum value of specific capacitance of 277 F/g at scan rate of 5 mV/s was found in 1 M Na2SO4.•It shows long cycle stability.•The low value of RCT indicates fast ion/electron transport and rapid adsorption-desorption rates of ions in the electrode. We report simple and cost effective production of water soluble graphene sheets using coal. The synthesized coal derived graphene (CDG) sheets were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), Raman, Fourier transform infrared (FTIR), ultra-violet visible (UV–vis) spectroscopy, and photoluminescence (PL) measurements. The presence of edge oxygen functionalities in CDG sheets causes to induce fluorescent properties. The nature emission peak does not change with varying the excitation wavelength. To determine its energy storage properties, cyclic voltammetry (CV), charge-discharge and electrochemical impedance spectroscopy (EIS) measurements were done in different electrolytes. The value of specific capacitance (SC) of CDG in 1 M Na2SO4 electrolyte turns out to be 277 F/g at scan rate of 5 mV/s. CDG show long cycle stability i.e., the value of SC remains at ~91% after 2000 cycles at the current density of 10 mA/g.