Direct observation of phase change accommodating hydrogen uptake in bimetallic nanoparticles

Abstract

Hydrogen holds great promise as a cleaner alternative to fossil fuels, but its efficient and affordable storage remains a significant challenge. Bimetallic systems, such as Pd-Ni, present a promising option for storing hydrogen. In this study, using the combination of different cuttingedge X-ray and electron techniques, we observed the transformations of Pd-Ni nanoparticles, which initially consist of a NiO-rich shell surrounding a Pd-rich core but undergo a major transformation when interacting with hydrogen. During the hydrogen exposure, the Pd core breaks into smaller pockets, dramatically increasing its surface area and enhancing the hydrogen storage capacity, especially in nanoparticles with lower Pd content. The findings provide deep understanding of the morphological changes at the atomic level during hydrogen storage and contribute for designing cost-effective hydrogen storage using multi-metallic systems.