Revealing Compositional Evolution of PdAu Electrocatalyst by Atom Probe Tomography

Abstract

Pd-based electro-catalysts are a key component to improve the methanol oxidation reaction (MOR) kinetics from alcohol fuel cells. However, the performance of such catalysts is degraded over time. To understand the microstructural/atomic scale chemical changes responsible for such an effect, scanning (transmission) electron microscopy measurements and atom probe tomography were performed after accelerated degradation tests. No morphological changes are observed after 1000 MOR cycles. In contrast, (1) Pd and B are leached from PdAu nanoparticles and (2) Au-rich regions are formed at the surface of the catalyst. These insights highlight the importance of understanding the chemical modification occurring upon MOR to design new catalysts.