Pt/C Electrocatalyst Synthesis from Recycling of the Spent PEMFC Membrane Electrode Assembly: A Closed Loop Circular Economy

Large-scale commercialization and sustainable growth of proton exchange membrane fuel cells (PEMFCs) technology depends largely on availability of the raw materials. Here, technical details of a closed loop recycling of spent electrocatalyst from a PEMFC electrode is demonstrated. The process includes electrochemical dissolution of the Pt nanoparticles in dilute acidic bath, precipitation of the dissolved Pt in form of a Pt-salt and synthesis of carbon supported Pt (Pt/C) electrocatalyst through reduction of the Pt-salt. Spent electrocatalysts from PEMFC electrodes, owing to their high activity, were subjected to dissolution through potentiodynamic treatment in dilute (0.1 M or 1 M) HCl bath to attain a Pt concentration of ∼0.7 mg/mL. Pt was recovered from the electrolyte by precipitation in form of ammonium hexachloroplatinate, which was converted to Pt/C electrocatalyst (20 wt% Pt) through reduction by refluxing in an ethylene glycol/water (1:1 v/v) mixture. Electrochemical surface area measurement and accelerated stress test of the synthesized Pt/C exhibit performances similar to or better than that of commercial Pt/C (20 wt% Pt). With a demonstrated recovery efficiency >90%, the process may be utilized for large-scale recycling of the spent electrocatalysts, especially suitable for PEMFC electrodes.