Au@Pd Nanostructures With a Porous Morphology and Their Enhanced Catalytic Activity Toward Formic Acid Oxidation

We report a facile synthesis of Au@Pd nanostructures with controllable porous shells by varying the concentration of KBr. Our mechanistic studies suggest that the porous morphology can be ascribed to an attachment growth process. Rapid reduction of Pd(II) precursor generates abundant Pd atoms in the initial stage of a synthesis. The Pd atoms self‐nucleate in the solution to generate a large number of ultrafine nanoparticles, which are subsequently deposited onto the surface of Au seeds through attachment growth. Increasing the concentration of KBr slows down the reduction kinetics, leading to the formation of fewer and larger Pd nanoparticles for the generation of less porous shells. A tensile lattice strain is identified in the Pd shell, providing more active catalytic sites. When evaluated as electrocatalysts toward formic acid oxidation, the porous Au@Pd nanocrystals exhibit a current density of 2.50 A mg −1 , approximately six times greater than that of the commercial Pd/C, highlighting their great potential for applications in direct formic acid fuel cells.