Utilizing Waste Thermocol Sheets and Rusted Iron Wires to Fabricate Carbon–Fe₃O₄ Nanocomposite-Based Supercapacitors: Turning Wastes into Value-Added Materials

The synthesis of porous activated carbon (specific surface area=1883 m² g⁻¹), Fe₃O₄ nanoparticles, and carbon–Fe₃O₄ (C−Fe₃O₄) nanocomposites from local waste thermocol sheets and rusted iron wires is demonstrated herein. The resulting carbon, Fe₃O₄ nanoparticles, and C−Fe₃O₄ composites are used as electrode materials for supercapacitor applications. In particular, C−Fe₃O₄ composite electrodes exhibit a high specific capacitance of 1375 F g⁻¹ at 1 A g⁻¹ and longer cyclic stability with 98 % capacitance retention over 10 000 cycles. Subsequently, an asymmetric supercapacitor, namely, C−Fe₃O₄∥Ni(OH)₂/carbon nanotube device, exhibits a high energy density of 91.1 Wh kg⁻¹ and a remarkable cyclic stability, with 98 % capacitance retention over 10 000 cycles. Thus, this work has important implications not only for the fabrication of low-cost electrodes for high-performance supercapacitors, but also for the recycling of waste thermocol sheets and rusted iron wires for value-added reuse.