Investigation of Anomalous Co-Deposition of Cobalt and Nickel for Metal Recovery

Critical metals such as cobalt and nickel are essential for energy storage, catalysis, and

high-performance alloys in batteries, aerospace, and clean energy technologies. As global

demand outpaces mining supply, sustainable recovery methods are urgently needed.

Electrodeposition offers a promising approach for selective metal recovery from aqueous

streams with minimal energy consumption and reduced chemical input compared to

conventional precipitation and solvent extraction methods.

This research investigates the electrochemical behavior of cobalt and nickel during

electrodeposition, focusing on optimizing conditions that maximize onset reduction potential

separation through anomalous co-deposition. Despite close standard reduction potentials, the

less noble metal can be preferentially deposited under specific conditions. Using cyclic

voltammetry and chronoamperometry, we systematically evaluated pH (4-6), temperature

(20-60°C), and applied voltage effects on selective deposition from sulfate electrolytes onto

copper substrates.

Results show that increasing temperature and pH shifts onset reduction potentials to less

negative values due to accelerated kinetics, with maximum separation between nickel and

cobalt at pH 5 and 60°C. Scanning electron microscopy and magnetic testing confirmed

successful deposition, with uniform films obtained at pH 4 and 50-60°C. Chronoamperometry

experiments proved high efficiency based on Faraday's law, validating electrodeposition viability.

However, hydrogen evolution reactions at certain conditions limited efficiency through bubble

formation blocking metal reduction sites.

This work establishes foundational parameters for selective electrochemical recovery of cobalt

and nickel. Future studies will explore EDTA complexation to simulate industrial wastewater and

chitosan as an eco-friendly polymer interface to enhance selectivity. These findings support

developing sustainable technologies for critical metal recovery, advancing circular economy

initiatives in clean energy sectors.