In situ Ni(II) to Ni(0) Reduction Enables Catalytic H2 Generation from Fe(II)-bearing Minerals
Abstract
Hydrogen is industrially produced at a scale of 70 million tons annually, with the majority of it derived from steam-methane reforming, an intensely emissions-heavy process. Vast reservoirs of mineralogical Fe(II) in the Earth’s subsurface and anthropogenic Fe(II) from steel slags represent an opportunity to stimulate mineralogical hydrogen by the reaction of hypoxic water with Fe(II)-rich phases, potentially allowing for both emissions-free and economically scalable hydrogen production. For select minerals, H 2 production from the coupled oxidation of Fe(II)-bearing solids is dramatically enhanced upon addition of Ni(II) ions, and mechanistic models posit that H 2 forms at co-precipitated Ni(II) sites bound to the ferrous substrate. Herein, we test this model by examining the temporal progression of the hydrogen evolution reaction (HER) driven by Fe(OH) 2 oxidation in presence of exogenous Ni(II). We find that Ni(II) is not the active catalyst, but instead serves as a pre-catalyst that is reduced in situ to metallic Ni(0) particles that then catalyze H 2 generation. This Ni(II) to Ni(0) conversion mechanism is also operative for hydrogen evolution from the mineral siderite (FeCO 3 ), suggesting that it may be a general mechanistic motif across ferrous minerals, which accelerates H 2 generation where HER is rate-limiting. These studies offer mechanistic insight into the in situ speciation of a catalyst commonly used for stimulated mineralogical hydrogen production, laying the foundation for further catalytic studies in the pursuit of evaluating and maximizing the potential of stimulated mineralogical hydrogen production.
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BibTeX
@misc{tan2026situ,
title = {{In situ Ni(II) to Ni(0) Reduction Enables Catalytic H2 Generation from Fe(II)-bearing Minerals}},
author = {Ephraem Tan and Anatole Borisov and Yogesh Surendranath},
howpublished = {ChemRxiv},
year = {2026},
month = aug,
doi = {10.26434/chemrxiv.15008064/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008064/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - In situ Ni(II) to Ni(0) Reduction Enables Catalytic H2 Generation from Fe(II)-bearing Minerals
AU - Ephraem Tan
AU - Anatole Borisov
AU - Yogesh Surendranath
PY - 2026
DA - 2026/08/31
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008064/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008064/v1
AB - Hydrogen is industrially produced at a scale of 70 million tons annually, with the majority of it derived from steam-methane reforming, an intensely emissions-heavy process. Vast reservoirs of mineralogical Fe(II) in the Earth’s subsurface and anthropogenic Fe(II) from steel slags represent an opportunity to stimulate mineralogical hydrogen by the reaction of hypoxic water with Fe(II)-rich phases, potentially allowing for both emissions-free and economically scalable hydrogen production. For select minerals, H 2 production from the coupled oxidation of Fe(II)-bearing solids is dramatically enhanced upon addition of Ni(II) ions, and mechanistic models posit that H 2 forms at co-precipitated Ni(II) sites bound to the ferrous substrate. Herein, we test this model by examining the temporal progression of the hydrogen evolution reaction (HER) driven by Fe(OH) 2 oxidation in presence of exogenous Ni(II). We find that Ni(II) is not the active catalyst, but instead serves as a pre-catalyst that is reduced in situ to metallic Ni(0) particles that then catalyze H 2 generation. This Ni(II) to Ni(0) conversion mechanism is also operative for hydrogen evolution from the mineral siderite (FeCO 3 ), suggesting that it may be a general mechanistic motif across ferrous minerals, which accelerates H 2 generation where HER is rate-limiting. These studies offer mechanistic insight into the in situ speciation of a catalyst commonly used for stimulated mineralogical hydrogen production, laying the foundation for further catalytic studies in the pursuit of evaluating and maximizing the potential of stimulated mineralogical hydrogen production.
ER -