Synergistic Strain and Electronic Effects in AuCu@CuFePd Core–Shell Nanocatalysts for Acidic Oxygen Reduction Electrocatalysis

Rational design of electrocatalysts that synergize lattice strain and electronic effect is pivotal for enhancing the oxygen reduction reaction (ORR) in acidic media. We, herein, report a core–shell AuCu@CuFePd nanocatalyst synthesized via sequential coreduction and galvanic replacement, where the AuCu alloy core induces interfacial compressive strain on the CuFePd shell, and synergistic interactions between Pd and incorporated transition metals (Cu/Fe) downshift the Pd d-band center, optimizing adsorption energies of oxygen intermediates. The catalyst exhibits a high half-wave potential of 0.85 V vs RHE, a specific activity of 1.33 mA cm^–2, and a mass activity of 1.46 A mg^–1, outperforming commercial Pd/C and most reported Pd-based catalysts in acidic media. This study demonstrates a generalizable strategy for engineering multimetallic nanostructures, offering both high-performance ORR catalysis in acidic environments and a blueprint for synergistic strain–electronic optimization in noble-metal electrocatalysts.