GQD-PAN-based high-performance supercapacitor: an approach towards wealth from waste

Abstract

Managing non-biodegradable polymeric waste and exploring efficient energy materials are imperative and need immediate attention. Herein, these two highly demanding problems were solved simultaneously by synthesizing nonpolar graphene quantum dots (GQDs) from non-biodegradable plastic waste and using the GQDs to fabricate energy storage systems. The GQDs were synthesized using styrofoam waste and coated on a carbonized polyacrylonitrile electrospun matrix (cPAN) to fabricate three- and two-electrode supercapacitors. A GQD coating of 0.4 mg led to an areal capacitance of 1883 mF cm⁻² (or a volumetric capacitance of 784 F g⁻¹) at 2 mA cm⁻² in a three-electrode supercapacitor, which was ∼78 times the capacitance produced in neat cPAN. The energy density also increased from 4 to 316.5 μW h cm⁻² compared to neat cPAN. In addition, the two-electrode supercapacitor exhibited high capacitance, energy density and power density values of 59.7 mF cm⁻², 10 μW h cm⁻² and 125 μW cm⁻², respectively. Additionally, both the three- and two-electrode supercapacitors maintained their capacitive behaviour for three thousand charge–discharge cycles. Thus, the approach developed in this work for the synthesis of efficient energy storage materials can be expanded to other plastic wastes for the generation of value-added products and unexplored applications, while addressing pertinent issues related to the environment.