Enhanced Oxygen Reduction Activity of Platinum Monolayer with a Gold Interlayer on Palladium

The activity of Pt monolayer supported on conventional (cuboctahedral) Pd nanoparticles for the oxygen reduction reaction was improved by 2-fold by introducing an Au submonolayer between the Pd core and Pt shell. By controlling the shape of the Pd cores (cubic and octahedral), we are able to distinguish the role of Au on the activity improvement at different facets. The Au interlayer can enhance the Pt monolayer activity toward oxygen reduction on both (100) and (111) surfaces, with the enhancement on (100) much more pronounced. The larger enhancement degree at the (100) sites may be due to the larger decrease of oxygen binding energy caused by Au interlayer (0.275 eV) than that at (111) sites (0.075 eV).