High‐Entropy Alloy Nanowires for Efficient and Durable Hydrogen Oxidation Reaction

Abstract High‐entropy alloy nanowires (HEA NWs) hold significant promise for achieving exceptional catalytic activity and stability, owing to their unique 1D morphology and the electronic engineering potential of the HEAs. However, the controlled synthesis of HEA NWs remains a challenge. In this work, a novel wet‐chemical approach is reported for the synthesis of ultrathin HEA NWs, represented by PtRuNiCuPb, through an active‐hydrogen (H·)‐mediated reduction mechanism. The H· species, generated by organic dehydrogenation, facilitate the effective co‐reduction of metal salts with differing reduction potentials, while the mild synthesis conditions ensure morphology control toward nanowire formation. The resulting PtRuNiCuPb HEA NWs exhibit remarkable catalytic activity in electrocatalytic hydrogen oxidation reaction (HOR) in alkaline media, due to their multimetallic compositions and abundant grain boundaries. At 50 mV, the specific and mass activities reach 8.46 mA cm ⁻² and 5.54 A mg _Pt+Ru ⁻¹ , respectively, ≈11.3 and 14.5 times greater than those of commercial Pt/C. Thanks to the unique 1D morphology, the PtRuNiCuPb HEA nanowires demonstrate excellent catalytic stability, retaining 97% of their initial mass activity after 20000 cycles of accelerated durability testing. These findings offer a promising strategy for designing highly efficient and durable catalysts using HEA compositions and 1D morphologies for electrocatalytic applications.