Atomic scale Pt decoration promises oxygen reduction properties of Co@Pd nanocatalysts in alkaline electrolytes for 310k redox cycles

Abstract

Nanocatalysts (NCs) with Co core–Pd shell structures and surface decoration of atomic scale Pt clusters (namely Co@Pd–Pt) are synthesized by using a self-aligned wet chemical reduction method in carbon nanotube supports. The Co@Pd–Pt contains ∼2.48 at% Pt metal. It shows a 30.2-fold mass activity (2056.3 mA mg⁻¹) of the Pt metal as compared to that of commercial Pt catalysts (67.1 mA mg⁻¹) at 0.85 volt (vs. RHE) and shows an exceptional stability of retained current density of ∼100% vs. the initial ones in an accelerated degradation test (ADT) for over 310k cycles in an alkaline electrolyte. The results of structural characterization and electrochemical analyses reveal that the high current density with substantial stability in the ORR is attributed to a strong electronic coupling and interface lattice that extract electrons from Co and Pd atoms in the presence of atomic Pt clusters in the Pd shell. A worth noticing finding is that such exceptional electrochemical performances are developed in a novel composition window in which Pt atoms are mostly positioned in defect sites of the Pd–Co interface in the shell region.