Eliminating dissolution of platinum-based electrocatalysts at the atomic scale

Abstract

A remaining challenge for deployment of proton-exchange membrane fuel cells is the limited durability of Pt-nanoscale materials that operate at high voltages during the cathodic oxygen reduction reaction. In this work, atomic-scale insight into well-defined single crystalline, thin-film, and nanoscale surfaces exposed Pt dissolution trends that governed the design and synthesis of durable materials. A newly defined metric, intrinsic dissolution, is essential to understanding the correlation between the measured Pt loss, surface structure, size and ratio of Pt-nanoparticles in carbon support. It was found that utilization of Au underlayer promotes ordering of Pt surface atoms towards (111)- structure, while Au on the surface selectively protects low-coordinated Pt sites. This mitigation strategy was applied towards 3 nm Pt3Au/C nanoparticles, resulting in elimination of Pt dissolution in liquid electrolyte, including 30-fold durability improvement vs. 3 nm Pt/C over extended potential range up to 1.2 V.