Hydroxyl Reservoir in Metal‐Bond‐Weakened PtFeSn Nanowires for Efficient Fuel Cell Catalysis

ABSTRACT Constructing an effective hydroxyl reservoir to optimize adsorption behavior of Pt‐based catalysts toward oxygen/carbon‐containing intermediates represents a key challenge for enhancing the CO tolerance of the anodic methanol oxidation reaction (MOR) and the kinetics of the cathodic oxygen reduction reaction (ORR) in fuel cells. Herein, we propose a Sn‐incorporation‐induced hydroxyl reservoir strategy for boosting MOR/ORR bifunctional electrocatalysis through metal‐bond‐weakened PtFeSn ternary alloy nanowires. Oxophilic Sn weakens Pt‐Pt bonds, induces lattice expansion, reduces electron sharing, and d ‐band center downshift, thus promoting H 2 O dissociation and OH supply, and forming a dynamic hydroxyl reservoir that provides stable oxygen species for *CO removal and *OH desorption. Consequently, the optimized Pt 77 Fe 16 Sn 7 exhibits exceptional MOR activity (2.07 A mg Pt −1 and 2.16 mA cm −2 ), excellent CO tolerance, and long‐term stability. For ORR, it achieves a half‐wave potential of 0.928 V and mass activity of 1.55 A mg Pt −1 , outperforming Pt 76 Fe 24 and Pt/C. In practical fuel cell devices, Pt 77 Fe 16 Sn 7 achieves a peak power density of 149 mW cm −2 in DMFC, while delivering 1.17 W cm −2 under H 2 ‐air conditions in PEMFC, with superior stability in both configurations. This work offers a new paradigm for atomic‐scale metal bond regulation toward high‐performance Pt‐based fuel cell catalysts.