Enriching the branching of Au@PdAu core–shell nanocrystals using a syringe pump: kinetics control meets lattice mismatch

We report the fabrication of gold@palladium–gold (Au@PdAu) nanocrystals with a highly branched shape via seeded growth. The success of the current work relies on the use of a syringe pump for dropwise addition of a bimetallic precursor to apply control over the reaction kinetics and an elevated reaction temperature to promote island growth mode as enabled by the coupling between surface diffusion and lattice mismatch. In particular, the one-shot injection of the bimetallic precursor at 60 °C and room temperature, respectively, resulted in the production of Au@PdAu nanocrystals with the shape of a concave cube and segmented branches, respectively, while dropwise addition of the bimetallic precursor at 60 °C led to the formation of a dendritic Pd–Au shell over the spherical Au seeds. When working as electrocatalysts, as compared to solid counterparts, the Au@PdAu core–shell nanodendrites exhibit an improved operation stability for electrooxidation of ethanol in alkaline media, demonstrating the advantage in morphology and structure.