One-Step Electrodeposition of Recycled Ni-Co Alloys from Spent Batteries: A Sustainable Route to High-Performance Water Oxidation Catalysts

The recovery and reuse of metals from electronic waste for catalyst preparation represents a promising strategy for addressing both energy crises and environmental pollution. In this study, nickel and cobalt were extracted from spent lithium-ion battery powder using a deep eutectic solvent, and the leachate was directly converted into an oxygen evolution reaction (OER) catalyst through electrodeposition without intermediate purification steps. The catalyst structure and electrochemical performance were systematically characterized. TEM/EDS confirmed the uniform distribution of nickel-cobalt alloy nanoparticles on carbon paper. Electrochemical measurements in 1 M potassium hydroxide electrolyte demonstrated that the optimized Ni5Co5(ox)(H2O)2/CP catalyst achieved overpotentials of 328 mV, 353 mV, and 375 mV at current densities of 10 mA cm⁻2, 20 mA cm⁻2, and 50 mA cm⁻2, respectively. The best-performing sample, Ni5Co5(ox)(H2O)2/CP-(-50)-30, exhibited catalytic activity approaching that of RuO2 on the same substrate (303 mV overpotential), indicating significant potential for water splitting applications. Furthermore, the catalyst maintained 97% of its initial current density after 80 hours of continuous OER operation, demonstrating excellent long-term stability.