From Waste to Value: End‐of‐Life Proton‐Exchange Membranes as Hydrogen Storage Materials at Mild Conditions

Proton‐exchange membranes (PEMs), such as Nafion, are central to hydrogen‐based electrochemical devices. The large‐scale disposal of end‐of‐life (EoL) membranes presents an urgent yet often overlooked challenge during the development of the hydrogen economy. This study reveals that EoL membranes can be directly repurposed as efficient hydrogen storage materials. The sub‐nano proton‐conducting channel network, preserved by water‐swelling and freeze‐drying procedure, provides rapid diffusion pathways for hydrogen, with its abundant sulfonic acid groups on the channel walls serving as effective chemisorption sites, while the in situ deposited precious metal atoms/clusters from long‑term operation act as highly efficient hydrogen spillover catalysts to catalyze H 2 into atomic H. The synergistic interplay of these features enables remarkable hydrogen storage under mild conditions. For example, a used Nafion membrane from a 200 h lifespan PEM fuel cell achieves a hydrogen storage capacity of 2.05 wt.% at 150°C and 5 MPa, along with excellent cycling stability and rapid kinetics. This performance is comparable to that of specially engineered hydrogen storage materials, highlighting its practical potential. The service‐evolved hydrogen storage functionality provides a sustainable and high‐value route for managing EoL electrochemical membranes.