Facile Synthesis of Trimetallic Hexoctahedral Au@PdPt Nanoparticles for Electrocatalytic Oxidation of Methanol

Abstract

In this study, trimetallic Au@PdPt nanoparticles (NPs) were synthesized by a seed-mediated technique, possessing a hexoctahedral (HOH) Au core with a branched PdPt alloy shell. The fabrication process involved the synthesis of HOH Au NPs exhibiting high-index {651} facet as nanotemplates, followed by the epitaxial growth of Pd and Pt on these NPs to yield HOH Au@PdPt NPs. The size and composition of HOH Au@PdPt NPs as well as the thickness of PdPt alloy shells (from 2 to 4, 5, and 8 nm) can be precisely adjusted by varying the quantity of Pd and Pt precursors. The catalytic efficacy of these Au@PdPt NPs was significantly enhanced through the synergistic effect between Au, Pd, and Pt, along with the increased contact areas afforded by multibranched PdPt alloy shells. For methanol electro-oxidation, the catalytic activity of HOH Au@PdPt NPs depends on the Pt content showing a distinctive volcano-type pattern. Remarkably, the HOH Au@Pd_0.3Pt_0.3 NPs demonstrate optimum catalytic performance for methanol oxidation in acidic conditions, exhibiting superior electrocatalytic properties compared to commercial Pt black catalysts. Their ECSA value, mass, and specific activities are 47.21 m² g^–1, 0.93 A mg^–1, and 1.97 mA cm^–2, respectively. This research can be exploited to fabricate catalysts possessing exceptional properties by precisely designing and controlling the size, composition and morphology of the trimetallic Au@PdPt NPs.