AuCu@Pd Core‐Shell Nanostructures With Surface Pd Atomic Steps for Efficient Electrocatalysis

Surface atomic steps serve as highly active sites for electrocatalysis, yet their controllable construction remains challenging. Herein, we report a facile strategy combining galvanic replacement and Au‐catalyzed reduction to fabricate AuCu@Pd core‐shell nanoparticles with dense surface Pd atomic steps on carbon substrate. Binary AuCu nanoalloy seeds were prepared via a Joule‐heating‐driven solid‐state diffusion method. Subsequently, Pd atoms substitute Cu atoms on the surface of AuCu alloy seeds, maintaining a flat surface morphology; next, Pd atoms selectively deposit on Au sites, forming atomic steps together with the Pd atoms that substituted Cu atoms in the last step. The optimized Au 10 Cu 5 @Pd 4 /C catalyst exhibits exceptional oxygen reduction reaction (ORR) performance in alkaline media, with a half‐wave potential of 0.92 V versus RHE, a specific activity of 1.29 mA cm −2 and a mass activity of 2.86 A mg Pd −1 , significantly outperforming commercial Pd/C. Control experiments verify that surface Pd atomic steps dominate the enhanced ORR activity. This strategy is further extended to synthesize AuCu@Pt nanoparticles with surface Pt steps, which show superior methanol oxidation activity. This work provides a universal approach to engineering surface atomic steps for high‐performance electrocatalysts.