Upcycling of electric arc furnace dust into ZnO-Fe₃O₄ nanocomposites for high-performance supercapacitor applications

The growing global demand for sustainable energy has driven extensive research into efficient energy storage systems. In this study, a novel approach is proposed for the upcycling of electric arc furnace dust (EAFD), a hazardous industrial waste into high-performance ZnO-Fe3O4 nanocomposites for use as supercapacitor electrodes. EAFD, rich in zinc and iron oxides, was processed through sulfuric acid leaching, co-precipitation, and thermal treatment, yielding nanostructured ZnO-Fe3O4. Under optimized conditions leaching efficiencies reached 98.3% for Zn and 90.1% for Fe. Subsequent co-precipitation at pH 8 successfully recovered both metals into a precursor with an efficiency greater than 99%. Following the thermal treatment, the synthesized nanocomposites were employed as electrode materials in asymmetric coin-cell supercapacitors. Electrochemical characterization demonstrated a specific capacitance of 35.2 mF cm-2, an energy density of 25.03 mu Wh cm-2, and a power density of 430.81 mu W cm-2 at a current density of 0.25 mA cm-2. Moreover, the device exhibited excellent cycling stability, retaining 81% of its initial capacitance after 7000 charge-discharge cycles. These findings demonstrate a scalable, eco-friendly approach for converting industrial waste into high-performance energy storage materials, aligning with circular economy principles and supporting environmental remediation.