Electrochemical Annealing Tailors PtCu Interlocked Networks Toward the Sabatier Optimum for Stable Oxygen Reduction

ABSTRACT Developing durable Pt‐based oxygen reduction reaction electrocatalysts is critical for commercializing proton exchange membrane fuel cells (PEMFCs). However, the conventional catalysts easily suffer from structural collapse and metal dissolution. We rationally design PtCu interlocked nanowire networks that synergistically integrate anisotropic 1D nanostructures with compressive lattice strains. This architecture enhances active site accessibility while weakening oxygen species adsorption. Aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) reveals the electrochemical annealing‐induced spontaneous welding at interwoven junctions during cycling, converting physical contacts into metallic bonds to resist agglomeration. Concurrent surface reconstruction generates a Pt‐rich shell that suppresses internal Cu dissolution. The catalyst achieves mass activity (MA) and specific activity (SA) of 1.68 A mg Pt −1 and 2.14 mA cm −2 at 0.90 V vs. RHE in 0.1 m HClO 4 , respectively, and sustains 93.68% MA after 40 000 accelerated durability testing (ADT) cycles. Mechanistic studies confirm electrochemical annealing simultaneously optimizes the adsorption energy of oxygen‐containing species on the catalyst surface and stabilizes the lattice framework. This work establishes electrochemical annealing as a transformative design paradigm for ultra‐stable strained nanoarchitectures.