Utilizing Waste Thermocol Sheets and Rusted Iron Wires to Fabricate Carbon-Fe3 O4 Nanocomposite-Based Supercapacitors: Turning Wastes into Value-Added Materials.

The synthesis of porous activated carbon (specific surface area=1883 m2  g-1 ), Fe3 O4 nanoparticles, and carbon-Fe3 O4 (C-Fe3 O4 ) nanocomposites from local waste thermocol sheets and rusted iron wires is demonstrated herein. The resulting carbon, Fe3 O4 nanoparticles, and C-Fe3 O4 composites are used as electrode materials for supercapacitor applications. In particular, C-Fe3 O4 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-Fe3 O4 ∥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.