Environmentally and Industrially Friendly Recycling of Platinum Nanoparticles Through Electrochemical Dissolution-Electrodeposition in Acid-Free/Dilute Acidic Electrolytes

A process to recycle platinum from industrial waste, for example, spent catalysts from polymer fuel cells and electrolyzers, through potentiodynamic dissolution along with potentiostatic electrodeposition in dilute acidic/acid-free baths has been explored. During potentiodynamic dissolution, owing to Ostwald ripening, redeposition of the dissolved Pt species on source nanoparticles becomes significant, leading to lower overall dissolution efficiency. Alternatively, high concentrations of Pt-complexing agents (e.g., Cl-) are required to stabilize dissolved species through complex formation. The present process overcomes those limitations by removing the dissolved Pt species continuously through electrodepositing them in the form of Pt-0 on another electrode. Such a process significantly promotes the overall reaction kinetics, and an increase in dissolution rate by a factor of two or more has been observed in non-complexing electrolytes. The process may be implemented for environmentally and industrially friendly recycling of Pt in dilute acidic/acid-free baths, thus eliminating the additional steps such as electrolyte upconcentration and post-dissolution reduction of dissolved Pt species.