Revealing High-Temperature Reduction Dynamics of High-Entropy Alloy Nanoparticles <i>via In Situ</i> Transmission Electron Microscopy.
basic_science · Level V
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- Record sourced from PubMed, PMID 33570961.
- Also identified by DOI 10.1021/acs.nanolett.0c04572.
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Abstract
Understanding the behavior of high-entropy alloy (HEA) materials under hydrogen (H<sub>2</sub>) environment is of utmost importance for their promising applications in structural materials, catalysis, and energy-related reactions. Herein, the reduction behavior of oxidized FeCoNiCuPt HEA nanoparticles (NPs) in atmospheric pressure H<sub>2</sub> environment was investigated by <i>in situ</i> gas-cell transmission electron microscopy (TEM). The reduction reaction front was maintained at the external surface of the oxide. During reduction, the oxide layer expanded and transformed into porous structures where oxidized Cu was fully reduced to Cu NPs while Fe, Co, and Ni remained in the oxidized form. <i>In situ</i> chemical analysis showed that the expansion of the oxide layer resulted from the outward diffusion flux of all transition metals (Fe, Co, Ni, Cu). Revealing the H<sub>2</sub> reduction behavior of HEA NPs facilitates the development of advanced multicomponent alloys for applications targeting H<sub>2</sub> formation and storage, catalytic hydrogenation, and corrosion removal.