85 The Power of Hard Rocks: Driving the Energy Transition and Serving Society
This session examines how mafic and ultramafic rocks contribute to the energy transition by 1) generating hydrogen gas, 2) trapping CO2 through carbon mineralization, and 3) providing critical minerals for climate change mitigation and renewable energy production.
Monday, 20 October 2025
8:00 AM - 11:30 AM
HBGCC, 216AB
Nickel-Enhanced Hydrogen Generation During Low-Temperature Serpentinization: Insights from Synthetic Fluid Inclusion Microreactors
Paper number: 85-5
Program: Technical Sessions
Time: 9:15 AM – 9:30 AM
Authors
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Kyra RoyerThe University of Oklahoma, Norman, Oklahoma
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Hector LamadridThe University of Oklahoma, Norman, Oklahoma
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Orsolya GelencsérThe University of Texas at Austin, Austin, Texas
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Tongwei ZhangThe University of Texas at Austin, Austin, Texas
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Estibalitz UkarThe University of Texas at Austin, Austin, Texas
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Toti LarsonThe University of Texas at Austin, Austin, Texas
Abstract
Geologic hydrogen (H₂) generated via the hydration of Fe-rich minerals during serpentinization is a potential renewable energy source. However, while H₂ production during serpentinization is well documented, naturally accumulating hydrogen in quantities viable for extraction remains rare. To better assess the viability of geologic hydrogen as a carbon-free energy resource, it is essential to understand the low-temperature geochemistry that control its generation.
Past studies have established that factors like temperature, fluid composition, and reactive surface area strongly influence serpentinization. However, the role of trace metals—especially transition metals like Ni²⁺—in catalyzing hydrogen production has remained relatively unexplored. In this study, we used synthetic fluid inclusion (SFI) microreactors in San Carlos olivine to examine the effect of Ni²⁺ on H₂ production at 200 °C. Experimental fluids consisted of 3.5 wt.% NaCl and MgCl₂ in an 8:1 ratio, with varying concentrations of NiCl₂·6H₂O (0%, 5%, and 10% of a 0.17 M base). SFIs enabled in situ observation of reaction progress via visual inspection and Raman spectroscopy over several months. Serpentinization was initiated within 48 hours in all samples, indicated by the appearance of brucite, serpentine, and magnetite. Between days 5 and 7, a distinct Raman peak at ~4155 cm⁻¹ shift appeared in vapor bubbles, consistent with molecular hydrogen. The intensity of this signal increased over time and correlated positively with Ni²⁺ concentration. Experiments with 10% NiCl₂ showed the most rapid and sustained hydrogen generation, supporting a concentration-dependent catalytic effect.
These findings support a concentration-dependent catalytic role for Ni²⁺ in facilitating H₂ generation. This work demonstrates the effectiveness of SFIs for in situ reaction monitoring and emphasizes the importance of transition metals in controlling geologic hydrogen generation during serpentinization.
Geological Society of America Abstracts with Programs. Vol. 57, No. 6
doi: 10.1130/abs/2025AM-414478
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