Enhancing Oxygen Reduction Performance of Pt Monolayer Catalysts by Pd(111) Nanosheets on WNi Substrates

The dissolution of Pd and corrosion of carbon supports may reduce the stability of the Pt monolayer (ML) on Pd-based core catalysts, which will lead to a decrease in their electrocatalytic performances toward the oxygen reduction reaction (ORR). Herein, we report preparation of Pd(111) nanosheets (NS) onto carbon-supported WNi substrates using CO as a reducing and capping agent. Such Pd_NS/WNi layers can significantly enhance the ORR performance of a Pd_NS/WNi/C catalyst in alkaline and a Pt_ML/Pd_NS/WNi/C catalyst in acidic media. The dominating Pd(111) facets and consequently diminished low-coordination sites enhanced their electrocatalytic activity. Meanwhile, the inhibition of Pd–O formation bonds even at 1.1 V due to the presence of WNi/C substrates and additional shape-induced contraction caused by the slight Pd dissolution at the side edges resulted in the improvement in durability. Furthermore, the stability of the carbon supports was improved because of the protection from the well-covered WNi substrates.