Pyrolysis of waste plastics-derived carbon nanomaterials on nickel foam for utilization as an efficient binder-free electrode: Effect of catalyst loading on capacitive performance

The pyrolytic liquid and gas products are extensively analyzed for practical applications, but, few applications exist for solid product from waste plastics pyrolysis. This study investigates energy storage potential of waste plastics-derived carbon nano-materials (CNMs), pyrolyzed directly on nickel foam (NF) coated with nickel alumina catalyst, in a two-stage fixed bed reactor. Effect of increasing nickel to aluminum molar ratio (0.05, 0.1, 0.2) in energy storage capacity is studied. Galvanostatic charge-discharge curves, at 0.125 A g⁻¹, show highest specific capacitance of 153.75 F g⁻¹ for 0.1 molar ratio. The reason for such high performance is mainly because of a) greater metal-support interaction by using NF substrate, b) formation of CNMs according to base-growth mechanism, providing metal free surface at the top, and c) the presence of equal amounts of disordered and ordered carbons, resulting in meso- and micro-porous structures, providing high electrolyte availability at the electrode surface. The retained rectangle shape of cyclic voltammetry (CV) curve after 5000 cycles, with 98.5 % capacitance retention, also exhibits stability and durability of produced electrode. Though the fabricated electrode involved no post-treatment, yet, it showed higher performance than commercial CNMs. Therefore, this study open new ways to fabricate environment friendly and economically effective supercapacitors.