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.