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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

First-Principles Study of n -Butane Monomolecular Cracking and Dehydrogenation on Two-Dimensional-Zeolite Model Systems: Reaction Mechanisms and Effects of Spatial Confinement

Two-dimensional (2D) ultrathin (~0.5 nm) aluminosilicate bilayer films, consisting of hexagonal prisms (a.k.a. double 6-membered rings D6R) with acidic bridging hydroxyl groups exposed on the surface, have been previously synthesized on a Ru(0001) surface as a zeolite model system. These structures are helpful for mimicking zeolite catalysts with D6R building blocks, such as chabazite. We performed density functional theory calculations to investigate the monomolecular cracking and dehydrogenation of n-butane molecules over the acidic hydroxyl groups of the 2D model system and compared the reaction energetics with that in bulk chabazite. The intrinsic activation energy barrier is the highest for dehydrogenation and lowest for central C–C bond cracking in bulk chabazite. The trend of intrinsic energy barriers for dehydrogenation and terminal and central C–C bond cracking is reproduced on the 2D aluminosilicate film. Overall, the activation barriers are higher on the 2D film than in bulk chabazite due to the lack of confinement in the former. We further explored the effects of the zeolite channel size on the n-butane adsorption and monomolecular cracking using different bulk nanoporous zeolite frameworks (TON, MEL, MEI, and VFI). We found that as the confinement of channels decreases, n-butane adsorption becomes weaker, and the intrinsic energy barrier of terminal C–C cracking increases. The activation energy barriers (dehydrogenation and terminal and central C–C cracking) on the 2D bilayer film surface, which may be considered as zeolite cages at the infinite cage size limit, are close to that in VFI with a relatively large channel size. Comparing the reaction pathway of n-butane terminal C–C cracking in 3D nanocages and on the surface of the 2D aluminosilicate film revealed that stabilizing the transition states in the 3D nanocages is responsible for the decrease in the intrinsic energy barriers for bulk zeolites.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Organic Modifiers Promote Furfuryl Alcohol Ring Hydrogenation via Surface Hydrogen-Bonding Interactions

Interactions between surface adsorbed species can affect catalyst reactivity, and thus, the ability to tune these interactions is of considerable importance. Deposition of organic modifiers provides one method of intentionally introducing controllable surface interactions onto catalyst surfaces. In this study, Pd/Al2O 3 catalysts were modified with either thiol or phosphonic acid (PA) ligands and tested in the hydrogenation of furanic species. The thiol modifiers were found to inhibit ring hydrogenation (RH) activity, with the degree of inhibition trending with the thiol surface coverage. This suggests that thiols do not strongly interact with the reactants and simply serve to block active sites on the Pd surface. PAs, on the other hand, were found to enhance RH when furfuryl alcohol (FA) was used as the reactant. Density functional theory calculations suggested that this enhancement was due to hydrogen-bonding interactions between FA-derived surface intermediates and PA modifiers. Here, installation of hydrogen-bonding groups on the Pd surface served to preferentially stabilize RH product states. Furthermore, the promotional effect on the RH of FA was observed to be greater when a higher-coverage PA was used, providing a rate more than twice that of the unmodified Pd/Al2O 3 . The results of this work suggest that organic ligands can be designed to impart tunable surface interactions on heterogeneous catalysts, providing an additional method of controlling catalytic performance.

09 BIOMASS FUELS↗
DOE OSTI2021

An Iron(IV)–Oxo Intermediate Initiating l-Arginine Oxidation but Not Ethylene Production by the 2-Oxoglutarate-Dependent Oxygenase, Ethylene-Forming Enzyme

Ethylene-forming enzyme (EFE) is an ambifunctional iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenase. In its major (EF) reaction, it converts carbons 1, 2, and 5 of 2OG to CO 2 and carbons 3 and 4 to ethylene, a four-electron oxidation drastically different from the simpler decarboxylation of 2OG to succinate mediated by all other Fe/2OG enzymes. EFE also catalyzes a minor reaction, in which the normal decarboxylation is coupled to oxidation of L-arginine (a required activator for the EF pathway), resulting in its conversion to L-glutamate semialdehyde and guanidine. Here we show that, consistent with precedent, the L-Arg-oxidation (RO) pathway proceeds via an iron(IV)-oxo (ferryl) intermediate. Use of 5,5-[ 2 H 2 ]-L-Arg slows decay of the ferryl complex by >16-fold, implying that RO is initiated by hydrogen-atom transfer (HAT) from C5. That this large substrate deuterium kinetic isotope effect has no impact on the EF:RO partition ratio implies that the same ferryl intermediate cannot be on the EF pathway; the pathways must diverge earlier. Consistent with this conclusion, the variant enzyme bearing the Asp191Glu ligand substitution accumulates ~ four times as much of the ferryl complex as the wild-type enzyme and exhibits a ~ 40-fold diminished EF:RO partition ratio. Here, the selective detriment of this nearly conservative substitution to the EF pathway implies that it has unusually stringent stereoelectronic requirements. An active-site, like-charge guanidium pair, which involves the L-Arg substrate/activator and is unique to EFE among four crystallographically characterized L-Arg modifying Fe/2OG oxygenases, may serve to selectively stabilize the transition state leading to the unique EF branch.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

High-Energy Density Li-Ion Battery Cathode Using Only Industrial Elements

Li-ion batteries are crucial for the global energy transition to renewables; however, their scalability is limited by the supply of key elements used in commercial cathodes (e.g., Ni, Mn, Co, P). Therefore, there is an urgent need for next-generation cathodes composed of widely available and industrially scalable elements. Here, we introduce a Li-rich cathode based on the known material Li 2 FeS 2 , composed of low-cost elements (Al, Fe, S) that are globally mined and refined at an industrial scale. The substitution of redox-inactive Al 3+ for Fe 2+ achieves remarkably high degrees of anion redox, which, in turn, yields high gravimetric capacity (≈450 mAh·g –1 ) and energy density (≳1000 Wh·kg –1 ). We show that Al 3+ enables high degrees of delithiation by stabilizing the delithiated state, suppressing phase transformations that would otherwise prevent deep delithiation and extensive anion redox. This mechanistic insight offers new possibilities for developing scalable, next-generation Li-ion battery cathodes to meet pressing societal needs.

25 ENERGY STORAGE↗
DOE OSTI2026

A Quantitative Examination of Catalyst Component Impacts on Hydrogen Adsorption and Spillover

Hydrogen spillover is a widely recognized but poorly understood surface phenomenon. We coupled volumetric chemisorption with Fourier transform infrared spectroscopy, thermogravimetric analysis, and acid–base titrations to quantify the roles of metal (Pt, Au) and support chemistry (anatase, rutile, P25 titania) on spillover. We show that metal identity has little to no impact on the amount of spillover hydrogen. Spillover pressure dependence is essentially the same on Au/TiO 2 and Pt/TiO 2 , indicating H 2 adsorption is equilibrated across both the metal and support. Conversely, spillover is highly sensitive to support surface chemistry, as rutile TiO 2 stabilizes ∼5× more surface hydrogen than anatase TiO 2 . This change is due to a combination of factors, including the rutile surface’s higher proton affinity, stabilized surface electronic states, and larger surface entropy. This work highlights the utility of Au/MO x catalysts as control materials for spillover, as they enable quantitative evaluation of H 2 adsorption on active metals and spillover onto the support.

Adsorption↗
DOE OSTI2026

Controlled Placement of Trivalent Heteroatoms in MFI Zeolite Frameworks Using Structure-Directing Agents

MFI zeolites contain distinct confining pore environments, either smaller (∼0.55 nm) channels or larger (∼0.70 nm) intersections. The substitution of trivalent heteroatoms generates Brønsted acid sites of varying acid strength, which, together with their location within different pore environments, dictates the stability of transition states via electrostatic (ion-pair) and van der Waals interactions. Here, we report that structure-directing agents (SDAs) that control Al 3+ substitutional patterns during MFI crystallization analogously position other trivalent heteroatoms (Ga 3+ , Fe 3+ , B 3+ ), altering the distribution of acid sites between channels and intersections, as probed by low-temperature (403 K) toluene methylation kinetics. Heteroatom-substituted MFI crystallized with tetrapropylammonium result in low selectivity toward p-xylene (<30%), while those crystallized using (co-)SDAs containing peripheral hydrogen-bonding groups (e.g., ethylenediamine) show high p-xylene selectivity (∼80%). These selectivities are consistent with DFT-calculated Gibbs free energy barriers for intersection-dominant and channel-dominant active site distributions, respectively. Transition states to form each xylene isomer are similar in size and charge; thus, their rate constants decrease with acid strength similarly, causing isomer selectivity to depend strongly on confinement but not on acid strength. These generalizable synthetic strategies enable independently controlling acid site strength and location in MFI zeolites and, in turn, catalytic rates and selectivities.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Asymmetry underlies stability in power grids

Abstract Behavioral homogeneity is often critical for the functioning of network systems of interacting entities. In power grids, whose stable operation requires generator frequencies to be synchronized—and thus homogeneous—across the network, previous work suggests that the stability of synchronous states can be improved by making the generators homogeneous. Here, we show that a substantial additional improvement is possible by instead making the generators suitably heterogeneous. We develop a general method for attributing this counterintuitive effect to converse symmetry breaking , a recently established phenomenon in which the system must be asymmetric to maintain a stable symmetric state. These findings constitute the first demonstration of converse symmetry breaking in real-world systems, and our method promises to enable identification of this phenomenon in other networks whose functions rely on behavioral homogeneity.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2023

Strong parametric dispersive shifts in a statically decoupled two-qubit cavity QED system

Qubits in cavity quantum electrodynamic (QED) architectures are often operated in the dispersive regime, in which the operating frequency of the cavity depends on the energy state of the qubit, and vice versa. The ability to tune these dispersive shifts provides additional options for performing either quantum measurements or logical manipulations. Here we couple two transmon qubits to a lumped-element cavity through a shared superconducting quantum interference device (SQUID). In this work, our design balances the mutual capacitive and inductive circuit components so that both qubits are statically decoupled from the cavity with low flux sensitivity, offering protection from decoherence processes. Parametric driving of the SQUID flux enables independent, dynamical tuning of each qubit’s interaction with the cavity. As a practical demonstration, we perform pulsed parametric dispersive readout of both qubits. The dispersive frequency shifts of the cavity mode follow the theoretically expected magnitude and sign. This parametric approach creates an extensible, tunable cavity QED framework with various future applications, such as entanglement and error correction via multi-qubit parity readout, state and entanglement stabilization, and parametric logical gates.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Cooperative control of a DNA origami force sensor

Abstract Biomolecular systems are dependent on a complex interplay of forces. Modern force spectroscopy techniques provide means of interrogating these forces, but they are not optimized for studies in constrained environments as they require attachment to micron-scale probes such as beads or cantilevers. Nanomechanical devices are a promising alternative, but this requires versatile designs that can be tuned to respond to a wide range of forces. We investigate the properties of a nanoscale force sensitive DNA origami device which is highly customizable in geometry, functionalization, and mechanical properties. The device, referred to as the NanoDyn, has a binary (open or closed) response to an applied force by undergoing a reversible structural transition. The transition force is tuned with minor alterations of 1 to 3 DNA oligonucleotides and spans tens of picoNewtons (pN). The DNA oligonucleotide design parameters also strongly influence the efficiency of resetting the initial state, with higher stability devices (≳10 pN) resetting more reliably during repeated force-loading cycles. Finally, we show the opening force is tunable in real time by adding a single DNA oligonucleotide. These results establish the potential of the NanoDyn as a versatile force sensor and provide fundamental insights into how design parameters modulate mechanical and dynamic properties.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Molecular mechanism and structural basis of small-molecule modulation of the gating of acid-sensing ion channel 1

Acid-sensing ion channels (ASICs) are proton-gated cation channels critical for neuronal functions. Studies of ASIC1, a major ASIC isoform and proton sensor, have identified acidic pocket, an extracellular region enriched in acidic residues, as a key participant in channel gating. While binding to this region by the venom peptide psalmotoxin modulates channel gating, molecular and structural mechanisms of ASIC gating modulation by small molecules are poorly understood. Here, combining functional, crystallographic, computational and mutational approaches, we show that two structurally distinct small molecules potently and allosterically inhibit channel activation and desensitization by binding at the acidic pocket and stabilizing the closed state of rat/chicken ASIC1. Our work identifies a previously unidentified binding site, elucidates a molecular mechanism of small molecule modulation of ASIC gating, and demonstrates directly the structural basis of such modulation, providing mechanistic and structural insight into ASIC gating, modulation and therapeutic targeting.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Pt-Ligand single-atom catalysts: tuning activity by oxide support defect density

The support–metal interaction is an important element of heterogeneous catalyst design and is particularly critical for the rapidly growing field of single-atom catalysts (SACs). In this work, we investigate the impact of varying the defect density of the titania support on metal–organic Pt SACs for hydrosilylation reactions. Pt SACs are decorated on the powder titania support, employing a metal–ligand interaction with a dipyridyl-tetrazine ligand (DPTZ). The single-atom nature of Pt is verified by X-ray absorption spectroscopy (XAS) on both pristine and defective titania surfaces. These Pt species have a +2 oxidation state and are stabilized by bonding with DPTZ, surface oxygen, and residual chloride from the metal precursor. The catalytic activity is evaluated for the alkene hydrosilylation reaction and it is discovered that the activity of Pt-ligand is positively correlated with the defect density of the titania support. The turn-over number (TON) is calculated to be 12 530 for Pt SACs on a defective surface, which is significantly higher than Pt SACs on a pristine titania surface (830) for the same reaction period (10 min) under the same conditions (70 °C). We ascribe the high activity of Pt SACs on defective titania surfaces to two aspects: the coordination of Pt with more chloride than on pristine titania surfaces, which shortens the induction period of the reaction, and the preferential dispersion of Pt–DPTZ units on defective regions of titania surfaces, allowing facile contact between Pt sites and reactants. The supported Pt–DPTZ SACs show high stability through multiple cycles of batch reactions. This work demonstrates an efficient approach to improve the activity and stability of SACs by optimizing the metal–support interaction, which can also be applied to other oxide surfaces to further develop next-generation heterogeneous single-atom catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Splitting of multiple hydrogen molecules by bioinspired diniobium metal complexes: a DFT study

Splitting of molecular hydrogen (H 2 ) into bridging and terminal hydrides is a common step in transition metal chemistry. In this paper, we propose a novel organometallic platform for cleavage of multiple H 2 molecules, which combines metal centers capable of stabilizing multiple oxidation states, and ligands bearing positioned pendant basic groups. Using quantum chemical modeling, we show that low-valent, early transition metal diniobium(II) complexes with diphosphine ligands featuring pendant amines can favorably uptake up to 8 hydrogen atoms, and that the energetics are favored by the formation of intramolecular dihydrogen bonds. This result suggests new possible strategies for the development of hydrogen scavenger molecules that are able to perform reversible splitting of multiple H 2 molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

From machine learning to chemical insight: Darwinian chance and the stability of charge carriers in flow batteries

In chemistry, rationalizing and predicting reaction behavior in complex environments is challenging, but this knowledge is required for practical applications and materials advancement. Here, we focus on one such example that uses organic molecules as redox-active materials in electrochemical energy storage. In flow batteries, these molecules (also known as redoxmers) serve as charge carriers, and exceptional chemical stability in all states of charge is required for long-term use. Here, we show how machine learning combined with chemist's knowledge can be used to reveal patterns in the reactivity of charged redoxmers by providing mechanistically tractable clues.

25 ENERGY STORAGE↗
DOE OSTI2021

Terawatt attosecond x-ray source driven by a plasma accelerator

Plasma accelerators can generate ultra-high-brightness electron beams that open the door to light sources with a smaller physical footprint and properties un-achievable with conventional accelerator technology. In this paper, we show that electron beams from Plasma WakeField Accelerators can generate few-cycle coherent tunable soft x-ray pulses with TW peak power and a duration of tens of attoseconds, an order of magnitude more powerful, shorter, and with better stability than state-of-the-art X-ray Free Electron Lasers (XFELs). Such a light source would significantly enhance the ability to experimentally investigate electron dynamics on ultrafast timescales, having a broad-ranging impact across multiple scientific fields. Rather than starting from noise as in typical XFELs, the x-ray emission in this approach is driven by coherent radiation from a pre-bunched, high peak current electron beam of attosecond duration. This relaxes the restrictive tolerances that have hindered progress toward utilizing plasma accelerators as coherent x-ray drivers thus far, presenting a new paradigm for advanced accelerator light source applications.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Structural basis for severe pain caused by mutations in the S4-S5 linkers of voltage-gated sodium channel Na V 1.7

Gain-of-function mutations in voltage-gated sodium channel Na V 1.7 cause severe inherited pain syndromes, including inherited erythromelalgia (IEM). The structural basis of these disease mutations, however, remains elusive. Here, we focused on three mutations that all substitute threonine residues in the alpha-helical S4-S5 intracellular linker that connects the voltage sensor to the pore: Na V 1.7/I234T, Na V 1.7/I848T, and Na V 1.7/S241T in order of their positions in the amino acid sequence within the S4-S5 linkers. Introduction of these IEM mutations into the ancestral bacterial sodium channel Na V Ab recapitulated the pathogenic gain-of-function of these mutants by inducing a negative shift in the voltage dependence of activation and slowing the kinetics of inactivation. Remarkably, our structural analysis reveals a common mechanism of action among the three mutations, in which the mutant threonine residues create new hydrogen bonds between the S4-S5 linker and the pore-lining S5 or S6 segment in the pore module. Because the S4-S5 linkers couple voltage sensor movements to pore opening, these newly formed hydrogen bonds would stabilize the activated state substantially and thereby promote the 8 to 18 mV negative shift in the voltage dependence of activation that is characteristic of the Na V 1.7 IEM mutants. Our results provide key structural insights into how IEM mutations in the S4-S5 linkers may cause hyperexcitability of Na V 1.7 and lead to severe pain in this debilitating disease.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

CHARGE-MAP: An integrated framework to study the multicriteria EV charging infrastructure expansion problem

The widespread adoption of electric vehicles (EVs) in recent years has necessitated the development of effective charging infrastructures. However, charging infrastructure expansion is a multifaceted problem that requires careful consideration of the existing infrastructure, spatiotemporal distribution of charging demands, power-grid capacity, and budget constraints. Here, to approach this complex problem, we present CHARGE-MAP, a data-driven simulation-optimization framework, focused on ensuring meaningful charging experience for individual EV owners. CHARGE-MAP integrates three modules: an agent-based simulation module that estimates spatiotemporal distribution of charging demands by modeling EV adopter mobility and charging behavior; an optimization module that determines optimal new charging station/charger locations and capacities, while minimizing expected detour distances and wait-times with a limited number of new stations; and a power module that determines how to connect the stations to the power grid while maintaining its stability. Using the state of Virginia (consisting of 95 counties and 38 independent cities) as a case study, our results show that CHARGE-MAP can meet the demand of ~198,600 predicted EVs with 1,305 new public charging stations and 2,164 new chargers. It reduces average detour distances for charging by 66% and wait-times at stations by 72% compared to the existing infrastructure. Furthermore, transformer capacity requirement analysis reveals that only 1.8% of residential transformers require upgrades, while over 80% of commercial charging locations can be supported with modest transformer infrastructure (25 to 50 kVA). This indicates that targeted investments can facilitate cost-effective EV integration. Consequently, CHARGE-MAP provides policymakers and urban planners with crucial data-driven insights for effective EV charging infrastructure expansion. Sign up for PNAS alerts.

charging infrastructure↗
DOE OSTI2024

Fast rotation of nuclei with extreme isospin in the vicinity of neutron and proton drip lines

Abstract The analysis of the present understanding of collective rotation in very neutron-rich nuclei is presented. It is shown that collective rotation can lead to the increase of stability of rotational states with increasing spin. The detailed investigation of rotational excitations in very proton-rich nuclei confirms this conclusion and indicates that experimental studies of such features are more feasible in the nuclei near proton drip line. They also show that rotational bands which are proton quasi-bound at zero or low spins can be transformed into proton bound ones at high spin by collective rotation of nuclear systems. This is due to strong Coriolis interaction which acts on high-jor strongly mixed M orbitals and drives the highest in energy occupied single-particle states into negative energy domain. These physical mechanisms lead to a substantial extension of the nuclear landscape beyond the spin zero proton drip line. In addition, a new phenomenon of the formation of giant proton halos in rotating nuclei emerges: it is triggered by the occupation of strongly mixed M intruder orbitals.

Physics↗
DOE OSTI2024

Aeroelastic code comparison using the IEA 22MW reference turbine

Reference wind turbine designs and the associated aeroelastic models are widely used in both research and industry. Reference models representing future concepts are of particular interest. Current state of the art aeroelastic tools are relied upon to design the next generation of large wind turbines. However, modelling assumptions may be invalidated by upcoming very large turbines, and different aeroelastic tools may give inconsistent results. A 22MW turbine model has been defined as part of International Energy Agency (IEA) Wind Task 55 on Reference Wind Turbines and Farms to represent future turbines to be deployed in the 2030s. In this study, an aeroelastic model of this turbine has been created in four tools; Bladed, HAWC2, OpenFAST, and QBlade. Code comparisons are presented for steady state operation, linear stability analysis, and time domain power production simulations in steady and turbulent wind. Generally, the codes show a good agreement, but with some differences present in the linear stability analysis, periodic azimuthal variation, and time domain simulations. The models are a good basis for further study with the IEA 22MW turbine, and further code comparison exercises.

17 WIND ENERGY↗