Upcycling waste plastic into 2D-carbon nanomaterials for high-performance supercapacitors by incorporating NiCo₂O₄: a sustainable approach to renewable energy

A two-step catalytic pyrolysis technique is utilized to produce reduced graphene oxide (rGO) from waste plastic and a hydrothermal synthetic route to produce NiCo₂O₄ nanorods and NiCo₂O₄@WPrGO nanocomposites. The waste plastic derived reduced graphene oxide (WPrGO) provided the conductive network and stimulated the growth of NiCo₂O₄ nanorods on its surface in order to increase the collection and transportation of electrons during electrochemical charge storage performance. This technique makes NiCo₂O₄@WPrGO suitable for supercapacitor electrode materials. The electrochemical properties of the composites were evaluated using both two and three-electrode systems in 2 M KOH solution. The outstanding specific capacitance values of the NiCo₂O₄@WPrGO material and its symmetric prototype cell from CV and GCD were around 1566 F g⁻¹ and 400 F g⁻¹ (at scan rate of 2 mV s⁻¹) and 1105 F g⁻¹ and 334 F g⁻¹ (at current density of 0.5 A g⁻¹), respectively, with 2 M KOH electrolyte. Moreover, the assembled symmetric and asymmetric cell delivers high energy densities of 17 W h kg⁻¹ and 45.08 W h kg⁻¹ at the power densities of 153 W kg⁻¹ and 980 W kg⁻¹ respectively, along with high cycling stability of 86% and 88.5% after 15 000 and 3000 cycles, respectively.