One-pot sonication-assisted polyol synthesis of trimetallic core-shell (Pd,Co)@Pt nanoparticles for enhanced electrocatalysis

摘要

In this report, the synthesis and characterization of trimetallic (Pd,Co)@Pt nanoparticles (NPs) with Pt-enriched surfaces are detailed. (Pd,Co)@Pt NPs supported on carbon with different elemental compositions (Pd_(50)Co_(20)Pt_(30), Pd_(34)Co_(27)Pt_(39), and Pd_(21)Co_(34)Pt_(45)) are synthesized by sonochemical reactions of Pt(acac)_2, Pd(acac)_2, and Co(acac)_2 in ethylene glycol. The NPs are subsequently characterized by X-ray diffractometry, transmission electron microscopy, and inductively coupled plasma - atomic emission spectroscopy to determine their particle size, morphology, and elemental composition. The existence of a Pt-enriched surface on the (Pd,Co)@Pt NPs is demonstrated by line profiles obtained via scanning transmission microscopy - energy dispersive spectroscopy. The NPs are applied to electrocatalysis for oxygen reduction reactions. When compared to a commercial Pt catalyst, the onset potential of the NPs increased by 22 mV, while the specific and mass activities were enhanced by factors of ～ 2.7-4.9 and 4.3-6.3, respectively. The (Pd,Co)©Pt NPs also showed superior stability, as the onset potential was reduced by 11-19 mV after 5000 potential cycles when compared to the 45 mV reduction observed for a commercial Pt catalyst.