Oleylamine aging of PtNi nanoparticles giving enhanced functionality for the oxygen reduction reaction

TL;DR

This study presents a rapid synthesis method for PtNi nanoparticles with enhanced oxygen reduction reaction (ORR) activity, achieved through oleylamine aging that modifies surface composition and nanostructure.

Contribution

The paper introduces a novel oleylamine aging process that improves PtNi nanoparticle performance and durability for ORR, with detailed nanoscale compositional analysis.

Findings

Oleylamine aging induces Ni leaching and surface restructuring.

Aged nanoparticles show more than 2-fold catalytic performance improvement.

Mass-specific activity increases up to 25-fold compared to commercial catalysts.

Abstract

We report a rapid solution-phase strategy to synthesize alloyed PtNi nanoparticles which demonstrate outstanding functionality for the oxygen reduction reaction (ORR). This one-pot co-reduction colloidal synthesis results in a monodisperse population of single-crystal nanoparticles of rhombic dodecahedral morphology, with Pt enriched edges and compositions close to Pt1Ni2. We use nanoscale 3D compositional analysis to reveal for the first time that oleylamine (OAm)-aging of the rhombic dodecahedral Pt1Ni2 particles results in Ni leaching from surface facets, producing aged particles with concave faceting, an exceptionally high surface area and a composition of Pt2Ni1. We show that the modified atomic nanostructures catalytically outperform the original PtNi rhombic dodecahedral particles by more than 2-fold and also yield improved cycling durability. Their functionality for the ORR far exceeds commercially available Pt/C nanoparticle electrocatalysts, both in terms of mass-specific activities (up to a 25-fold increase) and intrinsic area-specific activities (up to a 27-fold increase).