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.