Palladium modified gold nanoparticles as electrocatalysts for ethanol electrooxidation

• Au@Pd core-shell catalysts consist of tiny Pd clusters with a coverage of 0.5–0.6.
• The Au@Pd is 5.4 times more active than Pd/C toward ethanol oxidation.
• The onset potential of ethanol oxidation is 100 mV lower than Pd/C.
• The larger the Au particle, the higher the ethanol oxidation current.

Resemblin, g core-shell electrocatalysts consisting of a Au core and Pd shell (Au@Pd) are synthesized via a Cu underpotential deposition (UPD)-Pd-displacement method. The Pd shell is non-uniform consisting of tiny Pd clusters with a coverage of 0.5–0.6. The ethanol oxidation reaction (EOR) activity of this kind of structure is much higher than Pd/C in an alkaline solution. The forward peak current density of Au@Pd is 5.4 times higher than that of Pd/C. Furthermore, the onset potential for EOR of the former is ∼100 mV more negative. An interesting particle size dependent EOR activity is also observed. With increasing the Au particle size (2.9, 5.8 and 6.5 nm), the EOR activity increases. The strain and ligand effects from the Au core, together with the bifunctional reaction mechanism in the Au–Pd system may be reasons for the enhanced activity in Au@Pd catalysts.

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