Core–Shell CuPd@NiPd Nanoparticles: Coupling Lateral Strain with Electronic Interaction toward High-Efficiency Electrocatalysis

Geometric structure and chemical composition are two critical factors that determine the electronic properties of an active metal favorable for a given catalytic reaction. In this scenario, we develop a wet-chemistry method to construct core–shell nanoentities consisting of a CuPd alloy core and a NiPd alloy shell, termed as CuPd@NiPd, which involves the synthesis of CuNi alloy seeds, and a subsequent galvanic replacement reaction with Pd2+ precursors in an organic medium at elevated temperature. In these unique core–shell nanostructures, the compressive lattice strain between core and shell regions and the electronic interaction between Pd and transitional elements could be coupled together to lead to a downshift of the d-band center of Pd sites, thus endowing them with good activity for catalyzing ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR). In particular, at an appropriate Pd/Cu precursor ratio of 1/1, the as-prepared core–shell CuPd@NiPd nanoparticles exhibit a mass activity of 5.1 A mg–1 for EOR and a half-wave potential of 0.91 V for ORR at room temperature in an alkaline medium, outperforming alloy CuPd, NiPd counterparts, commercial Pd/C, and the vast majority of recently reported Pd-based electrocatalysts.