Copper and iron extraction from chalcopyrite by NaCl@MgCl2@urea: Synthesis of CuFe2O4 electrodes for supercapacitors

• 3 mol/L NaCl yielded the highest copper (60%) and iron (23%) extraction from chalcopyrite, outperforming MgCl2 and MgCl2-urea mixtures. • Urea addition effectively reduced iron levels in the leach solution, enabling more selective copper enrichment. • Hydrothermal synthesis using MgCl2-urea leach solution produced 2D CuFe2O4 electrodes on nickel foam with 45–50 nm wall thickness. • CuFe2O4 electrodes achieved a specific capacitance of 725 mF/cm² at 2 mA/cm², demonstrating strong potential for supercapacitor applications.