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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Programmable Matter: The Nanoparticle Atom and DNA Bond

Colloidal crystal engineering with DNA has led to significant advances in bottom-up materials synthesis and a new way of thinking about fundamental concepts in chemistry. Here, programmable atom equivalents (PAEs), comprised of nanoparticles (the “atoms”) functionalized with DNA (the “bonding elements”), are assembled through DNA hybridization into crystalline lattices. Unlike atomic systems, the “atom” (e.g., the nanoparticle shape, size, and composition) and the “bond” (e.g., the DNA length and sequence) can be tuned independently, yielding designer materials with unique catalytic, optical, and biological properties. Here in this review, nearly three decades of work that have contributed to the evolution of this class of programmable matter is chronicled, starting from the earliest examples based on gold-core PAEs, and then delineating how advances in synthetic capabilities, DNA design, and fundamental understanding of PAE-PAE interactions have led to new classes of functional materials that, in several cases, have no natural equivalent.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Surface science of shape-selective metal nanocrystal synthesis from first-principles: Growth of Cu nanowires and nanocubes

The authors present results from first-principles density functional theory aimed at understanding the aqueous solution-phase growth of fivefold twinned copper nanowires and single-crystal nanocubes capped by hexadecylamine (HDA). The role of solution-phase chloride, present in the Cu salt or as an additive, is emphasized. Using ab initio thermodynamics, the authors delineate the range of solution-phase conditions, characterized by the chemical potentials of chloride and HDA, under which Cu nanowires and nanocubes can be grown. The authors discuss the likelihood of thermodynamic and/or kinetic nanostructures for various solution-phase concentrations. Their results are in good agreement with experiments and indicate that methods and insights developed for surface science in gas-phase or vacuum conditions can yield much insight into liquid-phase systems.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Modeling Oxidative Dehydrogenation of Propane with Supported Vanadia Catalysts Using Multireference Methods

The oxidative dehydrogenation of propane over supported vanadium oxide catalysts poses significant computational challenges due to complex electronic structure changes along the reaction coordinate, driven primarily by changes in the oxidation states of vanadium. To address these challenges, we systematically test quantum chemical methods, including multireference (MR) approaches, domain-based local pair natural orbital coupled cluster theory (DLPNO-CCSD(T)), and density functional theory (DFT). The initial C–H bond-breaking transition state requires MR treatment due to its multireference character, while subsequent steps permit efficient single-reference calculations. For the rate-limiting C–H activation step mediated by the vanadyl moiety, complete 1 active space second-order perturbation theory (CASPT2) yields an apparent activation barrier (E app 600K ) of 138 kJ/mol, consistent with experimental values (134 ± 4 kJ/mol; Gruene et al. Catal. Today 2010, 157, 137). In contrast, DLPNO-CCSD(T) overestimates this barrier (198 kJ/mol), whereas DFT predictions span 125–150 kJ/mol, depending on the functional. Our multireference investigation of this transition metal oxide-catalyzed process demonstrates that an active space that incorporates the C–H σ and V=O σ/π bonding orbitals, oxygen lone pairs, and their antibonding counterparts adequately captures electronic structure changes along the chemical transformation. Furthermore, these findings provide a general strategy for active space selection in transition metal oxide-catalyzed C/O–H bond activation reactions. The reference dataset from this work, which includes MR calculations with manually selected active spaces for all intermediates and transition states in the propane ODH reaction network, will serve as a benchmark for automating active space selection in similar systems.

Catalysts↗
DOE OSTI2022

3D printing of void-free glass monoliths: rheological and geometric considerations

Direct ink writing (DIW) is a versatile additive manufacturing technique capable of printing 3D architectures from a broad range of materials. The key advantage of DIW is the ability to spatially control both the architecture and the composition of the printed part, which enables the production of components with previously unachievable combinations of functionalities. One emergent application space for DIW has been in additively manufactured glass optics, where a “green body” is patterned layer-by-layer by extruding a silica-based slurry through a microfluidic nozzle and then thermally consolidated to transparent glass. A critical aspect of the process is ensuring that the printed part is completely free of voids that can occur in the interstitial spaces between the extruded filaments. This outcome is governed by the interplay between ink rheology and strains imposed by the printing process and geometric packing of the filaments. Here, we explore the strain- and rate-dependent deformation events in the DIW process to determine conditions that enable the printing of void-free monoliths without sacrificing shape fidelity. We focus on yield stress fluids consisting of fumed silica nanoparticles dispersed in organic solvents at varied volume fractions to control the rheological properties. We investigate the printability of these ink materials as a function of print process variables and devise the appropriate dimensionless parameters that capture the geometry-dependent and rate-dependent effects on the deformation of the extruded ink. Lastly, we use these scaling arguments to construct a phase diagram for void-free monolith printability.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Oxidative Dehydrogenation of N ‐Heteroaromatic Alkyl Alcohols and Amines Facilitated by Dearomative Tautomerization

The oxidation of alcohols, amines, and halides is a fundamental transformation in organic chemistry with significant applications in the synthesis of fine chemicals, pharmaceuticals, and natural products. Here we show that a broad variety of N-heteroarenes bearing hydroxymethyl, aminomethyl, or halomethyl groups are oxidatively dehydrogenated to their respective aldehydes by simply heating them in acidic or basic aqueous solution under ambient atmosphere. The quantitative oxidation of 9-acridinemethanol to 9-acridinecarboxaldehyde serves as an illustrative example, proceeding to completion within 3 hours in refluxing 5% aqueous acetic acid or even household vinegar. Quinoline derivatives may be similarly oxidized but require higher temperatures and longer reaction times, while indole derivatives are oxidized under basic conditions. Based on comprehensive regioselectivity screens, internal kinetic isotope competition, and density functional theory (DFT) calculations, we propose a mechanism in which migration of a methylene hydrogen to the pyridinic nitrogen by acid-catalyzed dearomative tautomerization yields an unstable enol or enamine intermediate that then irreversibly loses two hydrogen atoms to atmospheric oxygen. In addition to the simplicity and environmentally benign nature of our method, we observe no indication of any over-oxidation to carboxylic acids. Finally, we demonstrate the synthetic utility of this reaction through two different one-pot formylations of acridine.

Chemistry↗
DOE OSTI2021

The importance of kinematic twists and genuine saturation effects in dijet production at the Electron-Ion Collider

We compute the differential yield for quark anti-quark dijet production in high-energy electron-proton and electron-nucleus collisions at small x as a function of the relative momentum P ⊥ and momentum imbalance k ⊥ of the dijet system for different photon virtualities Q 2 , and study the elliptic and quadrangular anisotropies in the relative angle between P ⊥ and k ⊥ . We review and extend the analysis in [1], which compared the results of the Color Glass Condensate (CGC) with those obtained using the transverse momentum dependent (TMD) framework. In particular, we include in our comparison the improved TMD (ITMD) framework, which resums kinematic power corrections of the ratio k ⊥ over the hard scale Q ⊥ . By comparing ITMD and CGC results we are able to isolate genuine higher saturation contributions in the ratio Q s /Q ⊥ which are resummed only in the CGC. These saturation contributions are in addition to those in the Weizsäcker-Williams gluon TMD that appear in powers of Q s /k ⊥ . We provide numerical estimates of these contributions for inclusive dijet production at the future Electron-Ion Collider, and identify kinematic windows where they can become relevant in the measurement of dijet and dihadron azimuthal correlations. We argue that such measurements will allow the detailed experimental study of both kinematic power corrections and genuine gluon saturation effects.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Controlling kinetic and diffusive length-scales during absorptive hydrogen removal in methane dehydroaromatization on MoC x /H-ZSM-5 catalysts

Addition of Zr metal absorbent to MoC x /H-ZSM-5 in the form of staged-bed, stratified-bed, and interpellet physical mixtures effectively scavenges H 2 from catalyst proximity, enhancing maximum single-pass benzene + naphthalene yield during methane dehydroaromatization (DHA) reactions to 14-16% compared to 8% in formulations without zirconium. The coupling of spatially-distinct catalytic and absorptive functions is achieved by dispersive/diffusive transport which conveys H 2 to staged Zr both co- and counter-current to bulk advection, thereby suppressing axial H 2 partial pressure profiles along the catalyst bed and enhancing net aromatization rates. We evince hitherto unreported significance of dispersive hydrogen transport during methane DHA by measurement of Péclet number, Pe = 1.32, in H 2 tracer studies with step-change or impulse input to inert catalyst proxies. Kinetic limits to methane pyrolysis are quantified by Damköhler number, Da, for synthesis of benzene, Da B = 0.15, and naphthalene, Da N = 0.03, determined from kinetic studies which rigorously account for reversibility of DHA reactions. Here, detailed reaction-transport models synthesize interplay of kinetic, diffusive, and convective length-scales captured by Péclet and Damköhler number to predict influence of catalyst-absorbent proximity and process flow-conditions on aromatization rates. Systematic control of catalyst bed-length, L, or linear flow velocity, u, predictably alters Pe and Da to effect improvements in methane conversion with and without Zr metal, corroborating results from simulation of the reaction-transport model.

03 NATURAL GAS↗
DOE OSTI2019

Controlled Design of Phase- and Size-Tunable Monodisperse Ni 2 P Nanoparticles in a Phosphonium-Based Ionic Liquid through Response Surface Methodology

Nanoparticles of nickel phosphide are finding wide ranging utility as catalysts for hydrodesulfurization, hydrogen evolution reaction, and hydrodeoxygenation of bio-oils. Herein, we present a methodology to tailor monodisperse nickel phosphide nanoparticles in terms of size and phase through the use of a statistical response surface methodology. Colloidal nickel phosphide nanoparticles were synthesized by replacing octadecene (ODE), a commonly used organic solvent, by a more sustainable phosphonium-based ionic liquid (IL). The replacement of ODE with the phosphonium-based IL resulted in faster crystallization at lower temperatures to yield phase-pure, monodisperse Ni2P nanoparticles. Using a first-order design, the PPh3/Ni precursor ratio was identified as the most critical factor influencing the resulting size and phase of the nanoparticles. Optimization using a Doehlert matrix for second-order design yielded a second-degree polynomial equation used to predict the mean diameter of the nanoparticles (over a range of 4-12 nm) as a function of the PPh3/Ni precursor ratio and the temperature used during synthesis. The resulting model was validated by performing reactions using randomly chosen sets of conditions; the experimentally determined nanoparticle sizes were in excellent agreement with the theoretical sizes predicted by our model. This demonstrates the utility of a multivariate experimental design as a powerful tool in the development of synthetic strategies toward the preparation of colloidal nanoparticles with highly controlled size, size distribution, and phase.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Reduction of Plutonium(VI) to (V) by Hydroxamate Compounds at Environmentally Relevant pH

Natural organic matter is known to influence the mobility of plutonium (Pu) in the environment via complexation and reduction mechanisms. Hydroxamate siderophores have been specifically implicated due to their strong association with Pu. Hydroxamate siderophores can also break down into di and mono-hydroxamates and may influence Pu oxidation state, and thereby its mobility. In this study we explored the reactions of Pu(VI) and Pu(V) with a mono-hydroxamate compound (acetohydroxamic acid, AHA) and a tri-hydroxamate siderophore desferrioxamine B (DFOB) at environmentally relevant pH (5.5-8.2). Pu(VI) was instantaneously reduced to Pu(V) upon reaction with AHA. The presence of hydroxylamine was not observed at these pHs; however, AHA was consumed during the reaction. This suggests that the reduction of Pu(VI) to Pu(V) by AHA is facilitated by direct one electron transfer. Importantly, further reduction to Pu(IV) or Pu(III) was not observed, even with excess AHA. We believe that further reduction of Pu(V) did not occur because Pu(V) does not form a strong complex with hydroxamate compounds at circum-neutral pH. Experiments performed using desferrioxamine B (DFOB) yielded similar results. Broadly, this suggests that Pu(V) reduction to Pu(IV) in the presence of natural organic matter is not facilitated by hydroxamate functional groups and that other natural organic matter moieties likely play a more prominent role.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

To address surface reaction network complexity using scaling relations machine learning and DFT calculations

Surface reaction networks involving hydrocarbons exhibit enormous complexity with thousands of species and reactions for all but the very simplest of chemistries. We present a framework for optimization under uncertainty for heterogeneous catalysis reaction networks using surrogate models that are trained on the fly. The surrogate model is constructed by teaching a Gaussian process adsorption energies based on group additivity fingerprints, combined with transition-state scaling relations and a simple classifier for determining the rate-limiting step. The surrogate model is iteratively used to predict the most important reaction step to be calculated explicitly with computationally demanding electronic structure theory. Applying these methods to the reaction of syngas on rhodium(111), we identify the most likely reaction mechanism. Lastly, propagating uncertainty throughout this process yields the likelihood that the final mechanism is complete given measurements on only a subset of the entire network and uncertainty in the underlying density functional theory calculations.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Non-chemisorbed gold–sulfur binding prevails in self-assembled monolayers

Gold–thiol contacts are ubiquitous across the physical and biological sciences in connecting organic molecules to surfaces. When thiols bind to gold in self-assembled monolayers (SAMs) the fate of the hydrogen remains a subject of profound debate—with implications for our understanding of their physical properties, spectroscopic features and formation mechanism(s). Exploiting measurements of the transmission through a molecular junction, which is highly sensitive to the nature of the molecule–electrode contact, we demonstrate here that the nature of the gold–sulfur bond in SAMs can be probed via single-molecule conductance measurements. Critically, we find that SAM measurements of dithiol-terminated molecular junctions yield a significantly lower conductance than solution measurements of the same molecule. Through numerous control experiments, conductance noise analysis and transport calculations based on density functional theory, we show that the gold–sulfur bond in SAMs prepared from the solution deposition of dithiols does not have chemisorbed character, which strongly suggests that under these widely used preparation conditions the hydrogen is retained.

Inkpen, Michael S.↗
DOE OSTI2019

Synthesis of [18F]-γ-Fluoro-α,β-unsaturated Esters and Ketones via Vinylogous 18F-Fluorination of α-Diazoacetates with [18F]AgF

This communication reports a method for the vinylogous radiofluorination of α-diazoacetates to generate [18F]-γ-fluoro-α,β-unsaturated esters and ketones in moderate to good radiochemical yields. The method uses no-carrier-added [18F]AgF and is compatible with aromatic and non-aromatic substrates and a number of different functional groups. The labeling method is showcased in the synthesis of a fluorinated cholest-5-en-3-one derivative as well as a difluorinated product pertinent to drug discovery.

Chemistry↗
DOE OSTI2019

Probing the interplay between geometric and electronic-structure features via high-harmonic spectroscopy

We present molecular-frame measurements of the recombination dipole matrix element (RDME) in CO 2 , N 2 O, and carbonyl sulfide (OCS) molecules using high-harmonic spectroscopy. Both the amplitudes and phases of the RDMEs exhibit clear imprints of a two-center interference minimum, which moves in energy with the molecular alignment angle relative to the laser polarization. Here, we find that whereas the angle dependence of this minimum is consistent with the molecular geometry in CO 2 and N 2 O, it behaves very differently in OCS; in particular, the phase shift which accompanies the two-center minimum changes sign for different alignment angles. Our results suggest that two interfering structural features contribute to the OCS RDME, namely, (i) the geometrical two-center minimum and (ii) a Cooper-like, electronic-structure minimum associated with the sulfur end of the molecule. We compare our results to ab initio calculations using time-dependent density functional theory and present an empirical model that captures both the two-center and the Cooper-like interferences. We also show that the yield from unaligned samples of two-center molecules is, in general, reduced at high photon energies compared to aligned samples, due to the destructive interference between molecules with different alignments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Atom Probe Tomography for the Observation of Hydrogen in Materials: A Review

Atom probe tomography (APT) is an emerging microscopy technique that has high sensitivity for hydrogen with sub-nanometre-scale spatial resolution, which makes it a unique method to investigate the atomic-scale distribution of hydrogen at interfaces and defects in materials. This article introduces the basics of APT-based hydrogen analysis, particularly the challenge of distinguishing a hydrogen background signal in APT by using hydrogen isotopes, along with strategies to yield high-quality analysis. This article also reviews several important findings on hydrogen distribution in a range of materials, including both structural alloys and functional materials, enabled by using APT. Limitations and future opportunities for hydrogen analysis by APT are also discussed.

42 ENGINEERING↗
DOE OSTI2019

Perfect separation of intraband and interband excitations in PdCoO 2

The temperature dependence of the optical properties of the delafossite PdCoO 2 has been measured in the a-b planes over a wide frequency range. The optical conductivity due to the free-carrier (intraband) response falls well below the interband transitions, allowing the plasma frequency to be determined from the f-sum rule. Drude-Lorentz fits to the complex optical conductivity yield estimates for the free-carrier plasma frequency and scattering rate. Here, the in-plane plasma frequency has also been calculated using density functional theory. The experimentally determined and calculated values for the plasma frequencies are all in good agreement; however, at low temperature the optically determined scattering rate is much larger than the estimate for the transport scattering rate, indicating a strong frequency-dependent renormalization of the optical scattering rate. In addition to the expected in-plane infrared-active modes, two very strong features are observed that are attributed to the coupling of the in-plane carriers to the out-of-plane longitudinal optic modes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Nonperturbative-transverse-momentum effects and evolution in dihadron and direct photon-hadron angular correlations in p + p collisions at $\sqrt{s}$ = 510 GeV

Dihadron and isolated direct photon-hadron angular correlations are measured in p + p collisions at $\sqrt{s}$=510 GeV. Correlations of charged hadrons of 0.7 < p T < 10 GeV/c with $\pi$ 0 mesons of 4 < p T < 15 GeV/c or isolated direct photons of 7 < p T < 15 GeV/c are used to study nonperturbative effects generated by initial-state partonic transverse momentum and final-state transverse momentum from fragmentation. The nonperturbative behavior is characterized by measuring the out-of-plane transverse momentum component p out perpendicular to the axis of the trigger particle, which is the high-p T direct photon or $\pi$ 0 . Nonperturbative evolution effects are extracted from Gaussian fits to the away-side inclusive-charged-hadron yields for different trigger-particle transverse momenta ($p^{trig}_{T}$). The Gaussian widths and root mean square of p out are reported as a function of the interaction hard scale $p^{trig}_{T}$ to investigate possible transverse-momentum-dependent evolution differences between the $\pi$ 0 -h ± and direct photon-h ± correlations and factorization breaking effects. The widths are found to decrease with $p^{trig}_{T}$, which indicates that the Collins-Soper-Sterman soft factor is not driving the evolution with the hard scale in nearly back-to-back dihadron and direct photon-hadron production in p + p collisions. In conclusion, this behavior is in contrast to Drell-Yan and semi-inclusive deep-inelastic scattering measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

An ultrapotent synthetic nanobody neutralizes SARS-CoV-2 by stabilizing inactive Spike

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus enters host cells via an interaction between its Spike protein and the host cell receptor angiotensin-converting enzyme 2 (ACE2). By screening a yeast surface-displayed library of synthetic nanobody sequences, we developed nanobodies that disrupt the interaction between Spike and ACE2. Cryo–electron microscopy (cryo-EM) revealed that one nanobody, Nb6, binds Spike in a fully inactive conformation with its receptor binding domains locked into their inaccessible down state, incapable of binding ACE2. Affinity maturation and structure-guided design of multivalency yielded a trivalent nanobody, mNb6-tri, with femtomolar affinity for Spike and picomolar neutralization of SARS-CoV-2 infection. mNb6-tri retains function after aerosolization, lyophilization, and heat treatment, which enables aerosol-mediated delivery of this potent neutralizer directly to the airway epithelia.

60 APPLIED LIFE SCIENCES↗