Structurally Modulated AuPd Alloy Nanorods for Plasmon-Promoted Methanol Electrooxidation

The spatial arrangement of plasmonic metals relative to catalytically active components directly governs the coupling efficiency between hot carriers and the local electromagnetic field at the catalytic interface, thereby profoundly affecting the activity and selectivity of plasmon-enhanced electrocatalytic reactions. However, relying solely on a catalytic metal as the dominant surface species often results in significant plasmon damping. At the same time, synergistically optimizing plasmonic enhancement and intrinsic catalytic activity through precise control of the composition, facets, and thickness of bimetallic alloys remains a major challenge in synthesis and structural design. In this study, Au@AuxPdy alloy core-shell nanorods with tunable shell composition and thickness were constructed, achieving a balance between plasmonic enhancement and intrinsic catalytic activity toward the methanol oxidation reaction (MOR). Through a combination of experimental observations, single-particle dark-field scattering spectroscopy, and numerical simulations, the alloy-shell-dependent extinction characteristics and their correlation with the plasmonic enhancement effect were elucidated. Under light irradiation, the optimal Au@Au5Pd5 nanorods show a 1.88-fold enhancement in current density for MOR. The as-designed bimetallic nanocatalysts can also be used as active substrates for in situ Raman spectroscopic studies of MOR. This work provides important insights for designing bimetallic nanostructures that integrate efficient plasmonic enhancement with high catalytic activity for plasmon-promoted catalysis.