Author Identifier (ORCID)
Kaveh Moghanirahimi: https://orcid.org/0009-0004-7677-3429
Stefan Iglauer: https://orcid.org/0000-0002-8080-1590
Alireza Keshavarz: https://orcid.org/0000-0002-8091-961X
Abstract
Despite recent efforts to investigate hydrothermal natural hydrogen production from magnetite, the effects of sample geometry and surface area on hydrogen yields remain inadequately characterized. This study compares hydrogen production from natural magnetite prepared as an intact slab versus fine powder under identical experimental conditions (pH 9, 200 °C, 103.4 bar, 60 days). The results show that magnetite powder yielded 0.052 mmol g−1 rock hydrogen, approximately fivefold higher than the slab. Comprehensive characterization of the magnetite slab revealed increased surface roughness after reaction. Quantitative XRD analysis showed substantial phase conversion from magnetite to hematite, consistent with oxidation of Fe2+ to Fe3+. SEM imaging indicated pronounced textural restructuring, including the development of euhedral crystal faces and enhanced microporosity, reflecting dissolution and reprecipitation processes. These results demonstrate that powders maximize hydrogen output through abundant reactive sites, whereas slabs, which are more representative of intact geological formations, exhibit lower specific yields governed by diffusion limitations and passivating hematite layers. These findings are particularly significant for both natural hydrogen production and geological hydrogen storage in magnetite bearing banded iron formations (BIFs) and other magnetite rich lithologies.
Keywords
Iron oxide transformation, magnetite-water interaction, surface characterization, surface reactivity
Document Type
Journal Article
Date of Publication
3-24-2026
Volume
220
Publication Title
International Journal of Hydrogen Energy
Publisher
Elsevier
School
School of Engineering
Funders
Commonwealth Scientific and Industrial Research Organisation (CSIRO) / Australian Research Council
Grant Number
ARC Number : DP220102907
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Comments
Moghanirahimi, K., Esteban, L., Shulakova, V., Ali, M., Iglauer, S., & Keshavarz, A. (2026). Geometry-driven controls on hydrothermal natural hydrogen generation from magnetite mineral. International Journal of Hydrogen Energy, 220, 154187. https://doi.org/10.1016/j.ijhydene.2026.154187