Combining Core-Shell Construction with Alloying Effect for High Efficiency Ethanol Electrooxidation: A Case of Core-Shell Au@Fepd Nanoparticles with Sub-Nano Alloy Shells

Combining the core-shell construction with an alloying effect is an effective way to optimize the electronic and lattice strain effects generated in core-shell configurations for achieving highly catalytic efficiency for a given electrochemical reaction. To demonstrate this concept, we herein report the use of core-shell Au@FePd nanoparticles with an Au core and a sub-nano FePd alloy shell to promote the electrocatalytic oxidation of ethanol. In these core-shell structures, the Au core modifies the electronic configuration of Pd atoms through differences in electronegativity, while the Fe component in thin shells reduces the lattice expansion of Pd induced by the Au core, both of which endows the Pd shell with an appropriate d-band center, favorable for the electrooxidation of ethanol molecules through C1 pathway. In particular, the as-prepared core-shell Au@FePd nanoparticles at an optimized Fe/Pd ratio of 0.5/1 (Au@FePd-0.5) exhibit a mass activity of 13.3 A mg-1 and a specific activity of 20.2 mA cm-2 for the ethanol electrooxidation in an alkaline medium, which significantly outperform those of a majority of the recent reported Pd-based electrocatalysts. This study highlights the concept of engineering the geometry and surface composition of a nanostructure for designing highly efficient electrocatalysts for a large variety of electrochemical applications.