Sustainable conversion of waste plastic into reduced graphene oxide for superior supercapacitor applications: A comparative electrolyte study

Abstract

The present study investigates the upcycling of waste polyethylene (PE) and polyethylene terephthalate (PET) into reduced graphene oxide (rGO) through a nanoclay-assisted melt mixing and pyrolysis process. A comparative electrochemical evaluation is performed using sulfuric acid (H₂SO₄), potassium hydroxide (KOH), and potassium chloride (KCl), electrolytes in a three-electrode configuration. The rGO derived from PE with 0.5 wt% nanoclay catalyst (PE_0.5-rGO) exhibits as the best performer, achieving a specific capacitance of 482.9 F/g at 0.5 A/g in 1 M H₂SO₄. Further testing in a two-electrode system reveals enhanced capacitance and excellent cyclic stability, underscoring the potential for practical applications. The fabricated device executes a maximum energy density of 53.5 Wh/kg at a power density of 280 W/kg. Additionally, this device shows remarkable long-term cycling stability, retaining approximately 83.1 % of its initial capacitance after 12,000 charge-discharge cycles. These findings demonstrate an efficient route for converting plastic waste into high-performance supercapacitor materials.