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At least 667 records · Page 37

All sources NASA NTRS DOE OSTI

DOE OSTI2020

A new platform for development of photosystem I based thin films with superior photocurrent: TCNQ charge transfer salts derived from ZIF-8

The transmembrane photosynthetic protein complex Photosystem I (PSI) is highly sought after for incorporation into biohybrid photovoltaic devices due to its remarkable photoactive electrochemical properties, chiefly driving charge separation with ~1 V potential and ~100% quantum efficiency. In pursuit of these integrated technologies, three factors must be simultaneously tuned, namely, direct redox transfer steps, three-dimensional coordination and stabilization of PSI aggregates, and interfacial connectivity with conductive pathways. Building on our recent successful encapsulation of PSI in the metal–organic framework ZIF-8, herein we use the zinc and imidazole cations from this precursor to form charge transfer complexes with an extremely strong organic electron acceptor, TCNQ. Specifically, the PSI-Zn-H 2 mim-TCNQ charge transfer salt complex was drop cast on ITO to form dense films. Subsequent voltammetric cycling induced cation exchange and electrochemical annealing of the film was used to enhance electron conductivity giving rise to a photocurrent in the order of 15 μA cm -2 . This study paves the way for a myriad of future opportunities for successful integration of this unique class of charge transfer salt complexes with biological catalysts and light harvesters.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

Nitric Oxide Production from Nitrite plus Ascorbate during Ischemia upon Hippocampal Glutamate NMDA Receptor Stimulation

Nitric oxide (•NO), a diffusible free radical, is an intercellular messenger, playing a crucial role in several key brain physiological processes, including in neurovascular coupling (NVC). In the brain, glutamatergic activation of the neuronal nitric oxide synthase (nNOS) enzyme constitutes its main synthesis pathway. However, when oxygen (O2) supply is compromised, such as in stroke, ischemia, and aging, such •NO production pathway may be seriously impaired. In this context, evidence suggests that, as already observed in the gastric compartment, the reduction of nitrite by dietary compounds (such as ascorbate and polyphenols) or by specific enzymes may occur in the brain, constituting an important rescuing or complementary mechanism of •NO production. Here, using microsensors selective for •NO, we show that nitrite enhanced the •NO production in a concentration-dependent manner and in the presence of ascorbate evoked by N-methyl-D-aspartate (NMDA) and glutamate stimulation of rat hippocampal slices. Additionally, nitrite potentiated the •NO production induced by oxygen-glucose deprivation (OGD). Overall, these observations support the notion of a redox interaction of ascorbate with nitrite yielding •NO upon neuronal glutamatergic activation and given the critical role of NO as the direct mediator of neurovascular coupling may represents a key physiological mechanism by which •NO production for cerebral blood flow (CBF) responses to neuronal activation is sustained under hypoxic/acidic conditions in the brain.

Nunes, Carla (ORCID:0000000274521592)↗

NASA NTRS2016

Authigenesis/Diagenesis of the Murray Formation Mudstone in Gale Crater, Mars

The Mars Science Laboratory rover Curiosity has been exploring sedimentary deposits in Gale crater since August, 2012. The rover has traversed up section through approximately 150 m of sedimentary rocks deposited in fluvial, deltaic, and lacustrine environments (Bradbury group and overlying Mount Sharp group). The Murray formation lies at the base of the Mt. Sharp group and has been interpreted to be a finely laminated mudstone likely deposited in a subaqueous lacustrine environment. Four drill samples from several elevations in the Murray fm have been acquired by the rover's sampling system and delivered to the CheMin XRD instrument. The lower section of the Murray fm contains 2:1 phyllosilicate(s), hematite, jarosite, XRD amorphous materials, and primary basaltic minerals. Further up section, the Murray fm contains magnetite, cristobalite, tridymite, abundant Si-rich XRD amorphous materials along with plagioclase and K-feldspars. Murray formation materials appear to have been altered under an open hydrologic system based on the bulk chemistry of these materials measured by the Alpha Particle X-ray Spectrometer (APXS). The 2:1 phyllosilicate only occurs in the lowermost section of the Murray fm and may be detrital or formed during authigenesis of Murray fm materials, similar to the Fe-saponite and magnetite detected in a mudstone in the Yellowknife Bay fm near Curiosity's landing site (stratigraphically at the base of the Bradbury group). The occurrence of jarosite and hematite in the lower section indicates an acidic diagenetic event. These phases may have formed via several acidic alteration mechanisms, including (1) oxidative weathering of mafic igneous rocks containing sulfides; (2) sulfuric acid weathering of Fe-bearing phases; and (3) near-neutral pH subsurface solutions rich in Fe2(+) that were rapidly oxidized to Fe3(+), which produced excess acidity. The transition from abundant hematite in the lowermost Murray fm to magnetite moving up section may indicate changes in lake chemistry, i.e., variable redox conditions, possibly during authigenesis or subsequent diagenetic events. Tridymite, a high temperature mineral, (and possibly cristobalite) is detrital, potentially deposited in a lake from a distal silicic volcanic rock source or from crustal materials present prior to the Gale Crater impact event. Abundant Si-rich XRD amorphous materials in the upper sections of the Murray fm may be detrital or an aqueous alteration product of primary igneous phases and phyllosilicates. Curiosity's science team is still deciphering the authigenesis and diagenetic events that formed the Murray fm. The mineralogy and geochemistry of the formation suggest a complicated history with several (many?) episodes of aqueous alteration under a variety of environmental conditions.

Ming, D. W.↗

DOE OSTI2021

Damage Modeling of Solid Oxide Fuel Cells Accounting for Redox Effects

This work applies a multiscale mechanistic damage model developed for brittle ceramics and implemented in commercial finite element (FE) packages via user subroutines to study progressive damage in solid oxide fuel cells (SOFC) subjected to thermomechanical loading under normal operating and shutdown conditions including redox effects. The damage model captures the micromechanics of stiffness reduction due to material porosity change and microcracking and integrates the as-obtained stiffness reduction law into a continuum damage mechanics (CDM) formulation for the evolution of microcracks up to fracture. The volumetric “swelling” that occurs during redox is treated in constitutive modeling similarly to thermal expansion, but swelling strains are irreversible. Furthermore, this damage model was first validated through predictions of strength and stress-strain response for the SOFC electrode materials. Next, it has been applied to predict the potential for degradation in a generic planar SOFC stack with large active area cells. Multicell stack models were simulated in both co-flow and counter-flow configurations. In addition, a constant temperature redox cycle was also simulated to capture overall cell electrode damage due to volumetric swelling of the nickel (Ni)-based anode in the anode-supported cells.

25 ENERGY STORAGE↗

DOE OSTI2025

A Cocatalytic System for Electrooxidation of Primary, Secondary, and Benzyl Alcohols Based on a Triruthenium Oxo-Centered Cluster and NHPI

Increasing interest in alternative methods for fuel generation and chemical synthesis has resulted in an increased focus on the development of electrocatalysts for energy relevant small molecule transformations, such as the oxidation of methanol. Partial methanol oxidation is a crucial step in the generation of the commodity chemical formaldehyde, and its complete oxidation to carbon dioxide can also serve as the anodic reaction in direct methanol fuel cells. We report a coelectrocatalytic system comprised of an oxo-centered triruthenium cluster (Ru 3 O) as the catalyst, with the electro-generated N-phthalimido-N-oxyl (PINO) radical species acting as a redox mediator. Only a mild Brønsted base, 2,6-lutidine, is required to achieve an electrocatalytic response. The cocatalytic system demonstrates remarkable cooperativity, shifting the oxidation potential of MeOH (Ep) less positive by ca. 0.5 V compared to the intrinsic response of the Ru 3 O complex. Controlled potential electrolysis on a model substrate, 4-trifluoromethylbenzyl alcohol, demonstrates selective production of the two-electron, two-proton aldehyde product with a Faradaic efficiency of 79 ± 11% at a rate of 3.14 s –1 . The rate of cocatalysis is 50-fold greater than the intrinsic activity of Ru3O and 26-fold greater than that of PINO alone under otherwise identical conditions. Mechanistic studies reveal the oxidation of a Ru 3 O–alkoxide species as the potential-determining step, while two possible rate-determining steps are identified depending on the substrate. A preference for sterically uninhibited electron-rich benzyl alcohol substrates suggests that a H atom transfer from the Ru 3 O–alkoxide adduct to PINO is rate-determining, while the lack of an observed kinetic isotope effect using deuterated MeOH suggests the oxidation of the Ru 3 O–alkoxide species is both rate- and potential-determining for cocatalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2026

Ion-Electron Coupling-Driven Redox Behavior in Metal–Organic Frameworks

Redox-active metal–organic frameworks (MOFs) have long been proposed as electronic transport platforms, yet the microscopic origin of their conductivity remains debated. A theoretical demonstration reveals charge transport in a Zn(pyrazole–naphthalene diimide (NDI)) MOF arising not from delocalized band-like states but from redox hopping between discrete linker sites. Using ab initio molecular dynamics simulations combined with electronic structure analysis, we established a direct link among electron injection, structural reorganization, and transport. Electron accumulation proceeds sequentially and site-selectively from imide and carbonyl groups of the NDI core progressively involving pyrazole N atoms at higher reduction states, through a hierarchy of redox-active sites. In contrast, Zn nodes remain essentially redox-inactive, which confirms their structural role. Density-of-states analysis corroborates a transport regime dominated by linker-centered states with evolving p-character upon reduction, resulting in dynamically reconfigured conduction networks. Real-time trajectories reveal anisotropic linker-to-linker electron transfer modulated by counterion coordination. This cooperative ion–electron regime emerges from potential energy surface collapse into a single low-barrier transition (ΔG ‡ ≈ 45 meV), where ionic and electronic motions evolve adiabatically on the same free-energy landscape. Elucidating redox conductivity in Zn(pyrazole–NDI) MOFs provides a theoretical framework for use in neuromorphic computing and related technologies.

Charge transfer↗

DOE OSTI2020

Biological Electron Transfer and Catalysis EFRC

The focus of the Biological Electron Transfer and Catalysis (BETCy) EFRC research is elucidating mechanisms of conversion of electrochemical potential into chemical bond energy and is organized into two integrated Thrusts: Electron Bifurcation Catalysis and Electron Transfer Kinetics. We are developing a collective knowledge of metalloenzymes as models for redox reactions by applying physical science and computational tools to characterize biochemical reactions catalyzed by multi- subunit enzymes harboring arrays of iron-sulfur clusters and flavin cofactors. Understanding these mechanisms is central to overcoming the thermodynamic barriers that currently limit production of reduced products and fuels. Biological systems have elegant strategies for converting electrochemical potential energy into chemical bond energy (e.g., C-H, H-H, and N-H) stored in reduced compounds that can serve as advanced biofuels. One significant limitation for the production of highly reduced compounds is that their production in natural and industrial processes relies on low oxidation-reduction potential chemicals as feedstocks.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

Tuning the Type 1 Reduction Potential of Multicopper Oxidases: Uncoupling the Effects of Electrostatics and H-Bonding to Histidine Ligands

In multicopper oxidases (MCOs), the type 1 (T1) Cu accepts electrons from the substrate and transfers these to the trinuclear Cu cluster (TNC) where O 2 is reduced to H 2 O. The T1 potential in MCOs varies from 340 to 780 mV, a range not explained by the existing literature. Here, this study focused on the ~350 mV difference in potential of the T1 center in Fet3p and Trametes versicolor laccase (TvL) that have the same 2His1Cys ligand set. A range of spectroscopies performed on the oxidized and reduced T1 sites in these MCOs shows that they have equivalent geometric and electronic structures. However, the two His ligands of the T1 Cu in Fet3p are H-bonded to carboxylate residues, while in TvL they are H-bonded to noncharged groups. Electron spin echo envelope modulation spectroscopy shows that there are significant differences in the second-sphere H-bonding interactions in the two T1 centers. Redox titrations on type 2-depleted derivatives of Fet3p and its D409A and E185A variants reveal that the two carboxylates (D409 and E185) lower the T1 potential by 110 and 255–285 mV, respectively. Density functional theory calculations uncouple the effects of the charge of the carboxylates and their difference in H-bonding interactions with the His ligands on the T1 potential, indicating 90–150 mV for anionic charge and ~100 mV for a strong H-bond. Finally, this study provides an explanation for the generally low potentials of metallooxidases relative to the wide range of potentials of the organic oxidases in terms of different oxidized states of their TNCs involved in catalytic turnover.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Acute Exposure to Aerosolized Nanoplastics Modulates Redox-Linked Immune Responses in Human Airway Epithelium

Micro- and nanoplastics (MPs and NPs) are pervasive environmental pollutants detected in aquatic ecosystems, with emerging evidence suggesting their presence in airborne particles generated by water body motion. Inhalation exposure to airborne MPs and NPs remains understudied despite documented links between occupational exposure to these particles and adverse respiratory outcomes, including airway inflammation, oxidative stress, and chronic respiratory diseases. This study explored the effects of acute NP exposure on a fully differentiated 3D human airway epithelial model derived from 14 healthy donors. Airway epithelium was exposed to aerosolized 50 nm polystyrene NPs at concentrations ranging from 2.5 to 2500 µg/mL for three minutes per day over three days. Functional assays revealed no significant alterations in tissue integrity, cell survival, mucociliary clearance, or cilia beat frequency, suggesting intact epithelial function post-exposure. However, cytokine and chemokine profiling identified a significant five-fold increase in CCL3 (MIP-1α), a neutrophilic chemoattractant, in NP-exposed samples compared to controls. This was corroborated by increased neutrophil chemotaxis in response to conditioned media from NP-exposed tissues, indicating a pro-inflammatory neutrophilic response. Conversely, levels of interleukins (IL-21, IL-2, IL-15), CXCL10, and TGF-β were significantly reduced, suggesting immunomodulatory effects that may impair adaptive immune responses and tissue repair mechanisms. These findings demonstrate that short-term exposure to NP-containing aerosols induces a distinct pro-inflammatory response in airway epithelium, characterized by enhanced neutrophil recruitment and reduced secretion of key immune modulators. These findings underscore the potential for aerosolized NPs to induce oxidative and inflammatory stress, raising concerns about their long-term impact on respiratory health and redox regulation.

Biochemistry & Molecular Biology↗

DOE OSTI2024

Insights on the structure and properties of sodium iron phosphate glasses from molecular dynamics simulations

Iron phosphate glasses are promising nuclear waste forms while more detailed understanding of their structures and structure-property relations are still needed to better design waste glass compositions. In this work we report studies of three series of sodium iron phosphate (NFP) glasses: 60P 2 O 5 -(40-x)Fe 2 O 3 -xNa 2 O (x = 0→40), (100–2x)P 2 O 5 -xFe 2 O 3 -xNa 2 O (x = 5→17.5) and one with different iron redox ratio, to understand the composition as well as the iron redox effects on the structure and properties of these glasses using molecular dynamics simulations with effective two-body and three-body potentials. Structural analyses, including pair distribution function, bond angle distribution, Q n distribution, and polyhedral connectivity, were performed to obtain in-depth information on short-range and medium-range structural features. The P-O pair distributions showed a first peak splitting with phosphorus-bridging and non-bridging oxygen contributions. This and the average P-O and other cation-oxygen bond distances are in excellent agreement with experiments. The coordination number of P 5+ remained four while that of Fe 3+ increased from 4.30 to 4.72 with decreasing Fe/Na ratio. Polyhedral linkage analysis showed [PO 4 ] units linked with [PO 4 ] and [FeO x ] through corner-sharing while the [PO 4 ]-[FeO x ] linkages become dominant for compositions with Fe 2 O 3 larger than 15 mol%. The effect of iron redox ratio on the structure of NFP glasses was also studied and it was found that bond lengths and coordination numbers were not strongly affected, while the reduction of iron introduced higher network distortions, as evident by O-P-O bond angle and Q n distribution. The glass transition temperature (T g ) showed a monotonic increase with Fe 2 O 3 in the first series, in good agreement with experiments, while those of the second series showed a maximum at P 2 O 5 = 82 mol%. Here, calculated elastic moduli were found to increase with Fe 2 O 3 in the first glass series, which was be explained by the increase of network connectivity, while those of the second series decrease with Fe 2 O 3 due to decrease of P 2 O 5 .

36 MATERIALS SCIENCE↗

DOE OSTI2022

CaMn 0.9 Ti 0.1 O 3 based redox catalysts for chemical looping – Oxidative dehydrogenation of ethane: Effects of Na 2 MoO 4 promoter and degree of reduction on the reaction kinetics

Reduction kinetics and stability of 20 wt% Na 2 MoO 4 -promoted CaMn 0.9 Ti 0.1 O 3 were investigated for its applications in Chemical Looping – Oxidative Dehydrogenation (CL-ODH) of ethane, a potential alternative for ethylene production with higher efficiency and lower emissions. Here, the present work reports a kinetics model and parameters for a Na 2 MoO 4 -promoted, Ti-doped CaMnO 3 (CaMn 0.9 Ti 0.1 O 3 ) redox catalyst under H 2 and C 2 H 4 . A first-order reaction model provides the best fit for the reduction of Na 2 MoO 4 /CaMn 0.9 Ti 0.1 O 3 under H 2 , while the C 2 H 4 reduction is well described by an Avrami–Erofe’ev model. The activation energy for C 2 H 4 oxidation is approximately three times higher than that for H 2 conversion, showing that the activation of C 2 H 4 is significantly more difficult on the surface of the redox catalyst. The reduction rate of Na 2 MoO 4 /CaMn 0.9 Ti 0.1 O 3 under H 2 at 750 °C is more than two orders of magnitude greater than that under C 2 H 4 , while the reduction rate of unpromoted CaMn 0.9 Ti 0.1 O 3 is comparable under H 2 and C 2 H 4 , showing that the addition of Na 2 MoO 4 effectively suppresses C 2 H 4 combustion relative to H 2 oxidation. The kinetics results for Na 2 MoO 4 /CaMn 0.9 Ti 0.1 O 3 confirm its excellent selectivity towards hydrogen combustion, making it a promising candidate under CL-ODH. Additionally, the stability of the CaMn 0.9 Ti 0.1 O 3 @ Na 2 MoO 4 core-shell structure, which was the underlying reason for the excellent selectivity, was examined under both shallow and deep reductions. It was determined that deep reduction of the redox catalyst, e.g. higher than 80% solid conversion, would lead to loss of sodium and hence to decreased selectivity for hydrogen combustion. In contrast, the core-shell structure was well-maintained, exhibiting excellent performance after 50 redox cycles when deep reduction of the redox catalyst was avoided. This study offers a basis for both the CL-ODH reactor design and redox catalyst optimizations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

Progresses and Perspectives of All‐Iron Aqueous Redox Flow Batteries

Abstract Redox flow batteries (RFBs) are a promising option for long‐duration energy storage (LDES) due to their stability, scalability, and potential reversibility. However, solid‐state and non‐aqueous flow batteries have low safety and low conductivity, while aqueous systems using vanadium and zinc are expensive and have low power and energy densities, limiting their industrial application. An approach to lower capital cost and improve scalability is to utilize cheap Earth‐abundant metals such as iron (Fe). Nevertheless, all‐iron RFBs have many complications, involving voltage loss from ohmic resistance, side reactions such as hydrogen evolution, oxidation, and most significantly electrode plating, and dendrite growth. To address these issues, researchers have begun to examine the effects of various alterations to all‐iron RFBs, such as adding organic ligands to form Fe complexes and using a slurry electrode instead of common materials such as graphite or platinum rods. Overall, progress in improving aqueous all‐iron RFBs is at its infant stage, and new strategies must be introduced, such as the utilization of nanoparticles, which can limit dendrite growth while increasing storage capacity. This review provides an in‐depth overview of current research and offers perspectives on how to design the next generation of all‐iron aqueous RFBs.

Belongia, Shawn↗

DOE OSTI2020

Cation Additive Enabled Rechargeable LiOH‐Based Lithium–Oxygen Batteries

Abstract Lithium–oxygen (Li–O 2 ) batteries have attracted extensive research interest due to their high energy density. Other than Li 2 O 2 (a typical discharge product in Li–O 2 batteries), LiOH has proved to be electrochemically active as an alternative product. Here we report a simple strategy to achieve a reversible LiOH‐based Li–O 2 battery by using a cation additive, sodium ions, to the lithium electrolyte. Without redox mediators in the cell, LiOH is detected as the sole discharge product and it charges at a low charge potential of 3.4 V. A solution‐based reaction route is proposed, showing that the competing solvation environment of the catalyst and Li + leads to LiOH precipitation at the cathode. It is critical to tune the cell chemistry of Li–O 2 batteries by designing a simple system to promote LiOH formation/decomposition.

Bi, Xuanxuan↗

DOE OSTI2020

Cation Additive Enabled Rechargeable LiOH-Based Lithium–Oxygen Batteries

Lithium-oxygen (Li-O 2 ) batteries have attracted extensive research interest due to their high energy density. Other than Li 2 O 2 (a typical discharge product in Li-O 2 batteries), LiOH has proved to be electrochemically active as an alternative product. Here we report a simple strategy to achieve a reversible LiOH-based Li-O 2 battery by using a cation additive, sodium ions, to the lithium electrolyte. Without redox mediators in the cell, LiOH is detected as the sole discharge product and it charges at a low charge potential of 3.4 V. A solution-based reaction route is proposed, showing that the competing solvation environment of the catalyst and Li+ leads to LiOH precipitation at the cathode. It is critical to tune the cell chemistry of Li-O 2 batteries by designing a simple system to promote LiOH formation/decomposition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Application of Fe-doped biochar in Cr(VI) removal from washing wastewater and residual Cr(VI) immobilization in contaminated soil

High-content Cr(VI)-contaminated soils are challenging to remediate using a single remediation technique. This study combined soil washing and immobilization to remediate high-content (3440 mg kg -1 ) Cr(VI)-contaminated soil, which investigated the effects of operating time, temperature, and liquid-solid ratio (LSR) on the Cr(VI) removal efficiency of soil washing and evaluated the potential of Fe-doped biochar (FeBC) in soluble Cr(VI) removal from the washing wastewater and residual Cr(VI) immobilization in the washed soil. The Cr(VI) removal efficiency of soil washing increased with the operating time, temperature, and LSR, but still cannot remove Cr(VI) to achieve the safety content (<100 mg kg -1 ). FeBC showed satisfactory potential in both Cr(VI) removal and immobilization from wastewater and soil, in which the main mechanisms involve ion exchange, redox, and coprecipitation. These results demonstrate applying soil washing & immobilization to remediate high-content Cr(VI)-contaminated soil is a promising alternative method.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2023

Determination of Ce 3+ , Co 2+ , Mn 2+ and Fe 2+ diffusion coefficients in Nafion® membrane

Concentration gradient diffusion coefficients for Ce 3+ , Co 2+ , Mn 2+ and Fe 2+ cations are determined in Nafion®211 membranes over a wide range of environmental conditions. Measurements are made using finite-width cation-rich bands introduced to NR211 via a hot-pressing procedure. A robust method of accurate diffusion coefficient determination of the finite-width deposits is developed using a Fick's second law of diffusion solution for one-dimensional systems. The transition metal dications are found to have nearly identical NR211 diffusion coefficients under water saturated conditions over the 22–80 °C range. The powerful chemical mitigant, Ce 3+ , is about one-half as diffusive as the dications under identical conditions. Derived diffusion coefficients for Ce 3+ and Co 2+ are found to be independent of initial cation concentration over the range of 12.5–70 mol% exchange level. The diffusion behavior of Ce 3+ in 80 °C liquid water and saturated water vapor is identical. The diffusion coefficients of Ce 3+ are shown to have a strong dependence on membrane hydration level varying by a factor of more than 30 over the range of 95 to 40% RH. Finally, the implications of these new diffusion findings are applied to a discussion of potential guidelines for the development of highly durable fuel cell systems, which employ mobile metal cations as lifetime-extending redox stabilizers.

08 HYDROGEN↗

DOE OSTI2025

Relationship between clay minerals and microorganisms in underground hydrogen storage reservoirs: a mini review

Hydrogen (H 2 ) will play a vital role in the global shift towards sustainable energy systems. Due to the high cost and challenges associated with storing hydrogen in large quantities for industrial applications, Underground Hydrogen Storage (UHS) in geological formations has emerged as a promising solution. Clay minerals, abundant in subsurface environments, play a critical role in UHS by providing low permeability, cation exchange capacity, and stability, essential for preventing hydrogen leakage. However, microorganisms in the subsurface, particularly hydrogenotrophic species, interact with clay minerals in ways that can affect the integrity of these storage systems. Microbes form biofilms on clay surfaces, which can cause pore clogging and reduce the permeability of the reservoir, potentially stabilizing H 2 storage and limiting injectivity. Microbial-induced chemical weathering, through the production of organic acids and redox reactions, can degrade clay minerals, releasing metal ions and destabilizing the storage site. These interactions raise concerns about the long-term storage capacity of UHS, as microbial processes could lead to H 2 loss and caprock degradation, compromising the storage system’s effectiveness. This mini review aims to cover the current understanding of the interactions between clay minerals and microorganisms and how these dynamics can affect the safe and sustainable deployment of UHS .

Clark, Allison↗

NASA NTRS2005

Anomalous Iridium Enrichment at the Triassic-Jurassic Boundary, Blomidon Formation, Fundy Basin, Canada

We present new analyses that confirm Ir enrichment (up to 0.31 ng/g) in close proximity to the palynological Triassic-Jurassic boundary in strata near the top of the Blomidon Formation at Partridge Island, Nova Scotia. High Ir concentrations have been found in at least two samples within the uppermost 70 cm of the formation. Ratios of other PGEs and Au to Ir are generally higher by an order of magnitude than in ordinary chondrites. No impact-related materials have been identified at #is horizon in the Blomidon Formation, therefore we cannot confirm an extraterrestrial source for the anomalous Ir levels. We consider, however, the possibility that regional basaltic volcanism is a potential source for the Ir in these sediments. The elevated Ir concentrations are found in reduced, grey colored mudstones, so redox concentration is a possible explanation for the distribution of Ir in these strata.

Kyte, Frank T.↗