Self-healing Pd3Au@Pt/C core-shell electrocatalysts with substantially enhanced activity and durability towards oxygen reduction

•Formation of various Pt shell layers on alloy-core via chemical reduction method.•Investigations of changed relation between core and shell after acceleration durability test.•Relationship between the electrocatalytic activities and durability in ADT and DFT calculations.

Pt shells were synthesized on Pd-based alloy-cores via the chemical reduction method. Pt shells containing 1, 2, or 3 layers were prepared by controlling the amounts of Pt precursor used during synthesis. The thicknesses of Pt shell layers were calculated using the difference in the particle size between core and core-shell nanocatalysts, as determined from Cs-corrected scanning transmission electron microscopy (Cs-STEM) data. The shape and elemental distribution in the core-shell structured nanoparticles were analyzed using line profiles and elemental mapping from Cs-STEM. High-resolution X-ray diffraction and X-ray photoelectron spectroscopy analyses suggested that the structural and electronic properties of core-shell nanocatalysts were dependent on the number of shell layers. The activity and durability of the core-shell nanocatalysts were analyzed by the electrochemical method. Accelerated durability tests (ADT) were conducted in the potential range of 0.6-1 V for 10000 cycles, and the mass and specific activities of ADT were shown to be stable for the carbon-supported core-shell nanocatalyst with two Pt shell layers (core@Pt[2](*)/C). In addition, excellent electrochemical performance was observed for the core@Pt[2]/C sample before and after the ADT compared to the commercial samples as well as other samples prepared in this study. Importantly, the optimized Pt usage demonstrated in this study would significantly contribute to the commercialization of proton exchange membrane fuel cells.

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