Validation on electrocatalyst closed-loop circularity for high temperature PEMFC electrodes: Pt recovery, electrocatalyst synthesis, and performance evaluation

Supply risk of Critical Raw Materials (CRMs) could be an essential bottleneck for further take-off of renewable energy conversion systems such as polymer electrolyte membrane fuel cells (PEMFCs). Here, we validate closed-loop recycling of Pt/C electrocatalyst from a high-temperature PEMFC (HT-PEMFC) stack. Due to their high hydrophobicity, Pt recovery from the HT-PEMFC electrodes poses different challenges compared to those in case of low-temperature PEMFCs; the recovery efficiency can be improved through enhanced mixing and reduced sample size. The Pt/C recycling process involved (i) Pt recovery, (ii) Pt/C synthesis and (iii) its electrocatalytic performance evaluation using half-cell and single cell configurations. The recovery of Pt was realized through a hydrometallurgical approach under mild conditions. Here, the overall Pt recovery efficiency of ∼83 % was achieved. Further, the recovered Pt was used to synthesize Pt/C electrocatalyst, which exhibited electrochemical performances comparable to that of the commercial reference Pt/C in half-cell configuration. Again, MEA with a 50 % recycled Pt/C blended anode shows a HT-PEMFC single cell polarization curve similar to that of a reference MEA, prepared using state-of-the-art Pt/C. The presented work demonstrates a viable route of sustainable material supply for HTPEM technologies and potentially beyond. • Closed-loop recycling of Pt/C from the spent high-temperature PEMFC is validated. • Recovery of Pt was achieved under mild conditions, utilizing the nanosize of Pt/C. • An overall Pt recovery efficiency of ∼83 % was achieved for the process. • Blending with fresh Pt/C is proposed as a strategy for adoption of recycled Pt/C. • MEA with a 50 % recycled Pt/C blended anode performs similar to a reference MEA.