PNNL

Abstract

The design and preparation of active and robust bimetallic catalysts require the understanding of the nanoscale alloying and phase-segregation structures. While platinum-based bimetallic catalysts have been widely explored for oxygen reduction reaction in fuel cells, little has been established for the correlation between the nanoscale phase structures and the catalytic properties. Here we describe new findings of the correlation between the nanoscale phase structures and the electrocatalytic properties of gold-platinum nanoparticles. The alloying and partial or complete phase-segregation were probed as a function of composition, size, thermal treatment temperature and duration by X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, electrochemical characterization, and density functional theory modeling. The unprecedented thermal control of the alloying and phase segregation provided the basis for establishing the nanostructure-catalysis correlation, which has immediate implications to the design and nanoengineering of a wide variety of advanced bimetallic functional nanostructures.