製鉄プロセスの革新：鉄生成のナノスケール観察に成功（Steel Making Could Get a Makeover）

2025-09-29 ミネソタ大学

＜関連情報＞

• https://cse.umn.edu/college/news/steel-making-could-get-makeover
• https://www.nature.com/articles/s41467-025-62639-4

ナノスケールオペランドTEMによる非熱プラズマによる鉄酸化物還元のメカニズムの解明 Revealing the mechanisms of non-thermal plasma-enabled iron oxide reduction through nanoscale operando TEM

Jae Hyun Nam,K. Andre Mkhoyan,Daan Hein Alsem & Peter J. Bruggeman
Nature Communications  Published:14 August 2025
DOI:https://doi.org/10.1038/s41467-025-62639-4

Abstract

H₂ plasma-enabled reduction of iron ore is a promising green alternative for reducing CO₂ emissions in the iron and steelmaking industry. In this work, we develop an operando plasma transmission electron microscopy (TEM) technique enabling the direct and real-time observation of magnetite (Fe₃O₄) nanoparticle reduction by non-thermal H₂ plasma with a spatial resolution of ~1 nm. Our operando results show a decrease in particle size accompanied by crack formation on timescales of ~10 s. We reveal that these observations are due to the oxide reduction, which induces a change in crystal structure from magnetite to iron, driven by the hydrogen radical, H^•. The operando reduction in particle volume by the plasma is well described by a shrinking-core reaction model. Our findings provide critical insights into mechanisms and rate-controlling processes of non-thermal iron ore reduction at the nanoscale. The developed operando plasma TEM technique is expected to find widespread application with the advent of non-thermal plasma technologies and the growing demands for diagnostic techniques to enhance mechanistic understandings in the field of plasma-nanoengineering.