Ionic liquid-derived core–shell gold@palladium nanoparticles with tiny sizes for highly efficient electrooxidation of ethanol

To maximize the size and structural advantages of nanomaterials in electrooxidation of ethanol, we herein report the synthesis of core–shell gold (Au)@Palladium (Pd) nanoparticles smaller than 3 nm in an ionic liquid, which combines the advantages of ionic liquids in preparing fine metal nanoparticles with the benefits of core–shell nanostructures. This synthetic strategy relies on the use of an ionic liquid (1-(2′-aminoethyl)-3-methyl-imidazolum tetrafluoroborate) as a stabilizer to produce Au particles with an average size of ca. 2.41 nm, which are then served as seeds for the formation of tiny core–shell [email protected] nanoparticles with different Au/Pd molar ratios. The strong electronic coupling between Au core and Pd shell endows the Pd shell with an electronic structure favorable for the ethanol oxidation reaction. In specific, the ionic liquid-derived core–shell [email protected] nanoparticles at an Au/Pd molar ratio of 1/1 exhibit the highest mass- and area-based activities, approximately 11 times than those of commercial Pd/C catalyst for ethanol electrooxidation.