Dynamic Ni–Fe Interfaces Regulate Stimulated Geological Hydrogen Production
- 1Department of Materials Science and Engineering
- 2Massachusetts Institute of Technology
- 3Department of Nuclear Science and Engineering
Abstract
Geological hydrogen (Geo-H2) generated by water-rock redox reactions could expand low-carbon hydrogen resources by tapping reducing equivalents stored in subsurface minerals. Stimulated Geo-H2 production remains difficult to engineer because the reaction sequence connecting rockhosted Fe2+ release to H2 evolution is incompletely constrained. Here, we support an interfacial sequence linking olivine Fe2+ release, an Fe(II)-bearing hydroxide intermediate state, Fe3O4bearing product growth, and Ni redistribution at evolving Fe-rich interfaces. Across olivine-rich rocks, basalt, and Fe(OH)2 model systems, trace dissolved Ni2+ enhanced H2 evolution over the examined temperatures, reaching rates more than two orders of magnitude above previously reported Geo-H2 systems at comparable temperatures, and dissolved Ni2+ outperformed solid Ni additives under matched additive-form comparisons. Fe-normalized controls show that dissolved Fe2+ alone produced far less H2 than Fe2+ converted to Fe(OH)2, supporting Fe(II)-hydroxide chemistry as a productive gateway to the magnetite-forming pathway. Electron microscopy, spectroscopy, and cross-sectional EDS connected olivine Fe redistribution with Fe-rich alteration products and Ni recruitment, whereas first-principles calculations indicated that adsorbed Ni-Fe sites stabilize dissociated H more strongly. The Ni response was finite, with excess loading suppressing H2 evolution through competing Ni2+ reduction and other high-Ni interfacial inhibitory pathways. These results connect Fe release, hydroxide-associated Fe(II) chemistry, magnetite-bearing product growth, and Ni loading and accessibility, providing an interfacial framework for promoting water reduction in stimulated Geo-H2 systems.
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BibTeX
@misc{gao2026dynamic,
title = {{Dynamic Ni–Fe Interfaces Regulate Stimulated Geological Hydrogen Production}},
author = {Yifan Gao and Jakob Krogh Nielsen and Seok Hee Han and Ming Lei and Haihui Lan and Yuheng Wu and William Gilstrap and Ju Li and Iwnetim I. Abate},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009395/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009395/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Dynamic Ni–Fe Interfaces Regulate Stimulated Geological Hydrogen Production
AU - Yifan Gao
AU - Jakob Krogh Nielsen
AU - Seok Hee Han
AU - Ming Lei
AU - Haihui Lan
AU - Yuheng Wu
AU - William Gilstrap
AU - Ju Li
AU - Iwnetim I. Abate
PY - 2026
DA - 2026/09/23
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009395/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009395/v1
AB - Geological hydrogen (Geo-H2) generated by water-rock redox reactions could expand low-carbon hydrogen resources by tapping reducing equivalents stored in subsurface minerals. Stimulated Geo-H2 production remains difficult to engineer because the reaction sequence connecting rockhosted Fe2+ release to H2 evolution is incompletely constrained. Here, we support an interfacial sequence linking olivine Fe2+ release, an Fe(II)-bearing hydroxide intermediate state, Fe3O4bearing product growth, and Ni redistribution at evolving Fe-rich interfaces. Across olivine-rich rocks, basalt, and Fe(OH)2 model systems, trace dissolved Ni2+ enhanced H2 evolution over the examined temperatures, reaching rates more than two orders of magnitude above previously reported Geo-H2 systems at comparable temperatures, and dissolved Ni2+ outperformed solid Ni additives under matched additive-form comparisons. Fe-normalized controls show that dissolved Fe2+ alone produced far less H2 than Fe2+ converted to Fe(OH)2, supporting Fe(II)-hydroxide chemistry as a productive gateway to the magnetite-forming pathway. Electron microscopy, spectroscopy, and cross-sectional EDS connected olivine Fe redistribution with Fe-rich alteration products and Ni recruitment, whereas first-principles calculations indicated that adsorbed Ni-Fe sites stabilize dissociated H more strongly. The Ni response was finite, with excess loading suppressing H2 evolution through competing Ni2+ reduction and other high-Ni interfacial inhibitory pathways. These results connect Fe release, hydroxide-associated Fe(II) chemistry, magnetite-bearing product growth, and Ni loading and accessibility, providing an interfacial framework for promoting water reduction in stimulated Geo-H2 systems.
ER -