Compressive Strain in Core-shell Au-Pd Nanoparticles Introduced by Lateral Confinement of Deformation Twinnings to Enhance The ORR Performance.

In this work, quasi-spherical, uniform gold nanoparticles with rich deformation twinning (Au NPs) were firstly synthesized with the assistance of copper (II) ions. Then, these Au NPs were used as the cores for the fabrication of core-shell (CS) Au-Pd NPs with ultrathin Pd layers, which also can bear compressive strain due to the formation of corrugated structured Pd shells led by the lateral confinement imposed by deformation twinning in the Au cores. The presence of compressive strain in the CS Au-Pd NPs can result in the widening of the d-band width of Pd shell and further the downshift of their d-band center, which then can improve the desorption ability to intermediates and still maintain the adsorption ability to the reactants due to the broad adsorption potential range. Taking the oxidation reduction reaction (ORR) and the ethanol oxidation reaction (EtOR) as examples, the as-prepared Au-Pd NPs indeed exhibited superior catalytic performances due to the synergism of compressive strain and electronic effect. Thus, our work opens a new way to introduce compressive strain in the Pd-based CS NP catalysts, which can achieve the enhancement in the electrocatalytic performance by combining the merit of compressive strain and electronic effect.