Au/Pd core-shell nanoparticles for enhanced electrocatalytic activity and durability

► Unique Au/Pd core-shell nanoparticles were synthesized via galvanic replacement of Cu by Pd on hollow Au spheres. ► The electronic coupling between the Pd shell and Au core was varied by the thickness of the former. ► The area-specific current densities of the Au/Pd catalysts are more than three times of the Pd black. ► The Au/Pd nanoparticles showed ~ 0.14 V lower CO oxidation potential than the commercial Pd black. ► The Au/Pd catalysts maintained 70% of the initial ECSA after 14,000 cycles.