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Mechanism of H 2 plasma-enabled reduction of hematite thin films

Singh, Binit B. [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000251615748)·Kumar, Sachin [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0009000105569349)·Krall, Eric A. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States). Laboratory for Energy Applications for the Future (LEAF)]·Goldman, Maxwell [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States). Laboratory for Energy Applications for the Future (LEAF)] (ORCID:0000000252675291)·Heo, Tae Wook [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States). Laboratory for Energy Applications for the Future (LEAF)]·Kortshagen, Uwe [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000159443656)·Bruggeman, Peter J. [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000333467275)
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Abstract

Hydrogen plasma is gaining significant interest as a promising pathway for direct iron ore reduction and for lowering process temperatures but the reduction mechanism remains poorly understood. In this work we analyzed the plasma and thermal reduction of thin-film hematite (Fe 2 O 3 ) at temperatures below 340 °C using X-ray diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Plasma reduced the incubation period by an order of magnitude and increased the reduction rate by a factor of 2.6 compared to thermal reduction. Plasma-produced H-atoms facilitate the formation of numerous iron nucleation sites, bypassing the energetically unfavorable dissociative adsorption of H 2 on iron oxide. These iron nuclei can autocatalyze the reduction of the surrounding hematite via a hydrogen spillover mechanism. Our results demonstrate that plasma-derived H-atoms primarily impact the initial nucleation-limited stage. These new insights provide a mechanistic framework that can aid the implementation and optimization of hydrogen plasma-assisted iron oxide reduction at reduced temperatures.

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Singh, Binit B. [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000251615748), Kumar, Sachin [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0009000105569349), Krall, Eric A. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States). Laboratory for Energy Applications for the Future (LEAF)], Goldman, Maxwell [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States). Laboratory for Energy Applications for the Future (LEAF)] (ORCID:0000000252675291), Heo, Tae Wook [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States). Laboratory for Energy Applications for the Future (LEAF)], Kortshagen, Uwe [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000159443656), Bruggeman, Peter J. [Univ. of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000333467275). 2026-06-01. Mechanism of H 2 plasma-enabled reduction of hematite thin films. https://doi.org/10.1016/j.ijhydene.2026.155624

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