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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Polymer-iron oxide hybrid films for controlling electrokinetic properties

Electrokinetic phenomena at polymer-water interfaces are central to technologies for water purification, ion separations, and energy conversion, yet the ability to systematically control polymer surface charge and associated electrokinetic processes remains limited. Here, we demonstrate a simple liquid-phase infiltration (LPI) method to synthesize polymer–metal oxide hybrid films with controllable interfacial properties. Hydroxy-terminated poly(2-vinylpyridine) (P2VP-OH) brushes grafted to silicon substrates were infiltrated with iron nitrate from ethanolic solution, followed by low-temperature thermal treatment to convert the infiltrated precursor into iron oxide. Spectroscopic ellipsometry, X-ray photoelectron spectroscopy, and thermogravimetric analysis confirmed oxide incorporation and hybrid film formation without polymer degradation. Electrokinetic measurements reveal that the hybrid films acquire the electrokinetic properties of the infiltrated oxide, with concentration-dependent streaming potentials and surface conductivities closely matching those of pure iron oxide films. These results establish metal oxide infiltration as a scalable and low-cost strategy for controlling interfacial charge in polymer surfaces. The approach introduces new materials and design parameters for tailoring ion selectivity, transport, and energy conversion, with broad implications for the development of advanced membranes, electrokinetic harvesting devices, and polymer-supported oxide electrodes.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Cation selectivities in zwitterion grafted nanopores: effect of zwitterion architecture

Selective separation of monovalent cations is a critical challenge in applications such as water purification and lithium recovery from salt brines. Cross-linked zwitterionic amphiphilic copolymer (ZAC-X) membranes have gained attention for their exceptional anion permselectivity, attributed to self-assembled zwitterion-lined nanodomains that interact preferentially with anions according to their hydrated radii r hyd . However, these membranes show minimal selectivity among monovalent cations, despite significant differences in their hydration structures, motivating studies on the underlying mechanisms of cation transport and selectivity in this family of materials. In this study, we conducted molecular dynamics simulations of aqueous salt solutions within zwitterion-functionalized nanopores to elucidate the influence of dipole orientation of the zwitterionic (ZI) ligands on cation diffusivities, partitioning, and permeabilities. To this end, we examined two contrasting ZI ligand architectures: Motif A (surface–cation–anion, S–ZI + –ZI − ) and Motif B (surface–anion–cation, S–ZI − –ZI + ). Our results show that in Motif A, the sulfonate groups of the ZI ligands are localized near the pore center radially, leading to strong electrostatic interactions with small bare cations (Mg 2+ and Li + ). This configuration results in high cation partitioning but low cation diffusion, maintaining solution-diffusion tradeoff typical of functionalized membranes. In contrast, Motif B show that sulfonate groups shift radially toward the mid-region of the pore. This shift, especially for small bare cations, introduces steric constraints that weaken their interactions with the sulfonate groups, thereby enhancing hydration and lowering partitioning, while still maintaining their low self-diffusivity. These findings establish zwitterion dipole orientation as a powerful design lever for tuning cation selectivity in membrane systems and offer molecular-level insights for engineering next-generation ion separation materials.

Morishita, Kazuya [Univ. of Texas, Austin, TX (Uni↗
DOE OSTI2026

pH-Driven Restructuring of Hydration Layers and Cation Adsorption at the Alumina–Water Interface

Oxide−water interfaces underpin ion separations, catalysis, and electrochemical energy technologies, where the electrical double layer (EDL) controls adsorption, transport, and reactivity. However, the molecular-scale links between pHdependent surface protonation, hydration-layer structure, and counterion adsorption remain poorly defined. Here, we combine in situ crystal truncation rod (CTR) and resonant anomalous X-ray reflectivity (RAXR) with streaming potential measurements and ab initio molecular dynamics (AIMD) simulations to resolve the chemical and structural evolution of the EDL at the single-crystal alumina (012)−water interface in 10 mM Rb + over pH 3−12. CTR measurements reveal two distinct adsorbed water layers at ∼2.2 and ∼3.5 Å above the surface. Each water layer shifts toward the substrate at transition pHs near 6.5 and 10.6, respectively, reflecting changes in primary hydration layer structure in response to the deprotonation of bridging and terminal aluminol groups. RAXR shows a 10-fold increase in Rb + coverage and a decrease in mean adsorption height from ∼3.5 to ∼2.7 Å with increasing pH, indicating enhanced counterion binding accompanied by Stern layer contraction. Streaming potential measurements demonstrate that the zeta potential, i.e., the potential at the hydrodynamic shear plane, is positive at pH 3 and becomes negative at pH ≥ 3.5. The negative charge magnitude increases with increasing pH, consistent with progressive surface deprotonation at higher pH. AIMD identifies inner- and outer-sphere Rb+ complexes whose adsorption heights and coordination geometries depend sensitively on the protonation state of surface oxygens, providing atomistic support for the experimentally inferred trends. These measurements establish two discrete, site-specific pH transitions in hydration-layer structure that track aluminol (de)protonation and quantitatively link them to a pH-driven contraction of the Stern layer (increasing Rb + coverage and decreasing adsorption height). This provides a direct structural basis for connecting surface acid−base chemistry to ion binding distances at an oxide−water interface.

Adsorption↗
DOE OSTI2023

Asymmetric vanadium-based aqueous flow batteries

Vanadium redox couples (V(II)/V(III) on a negative electrode or V(IV)/V(V) on a positive electrode) can be paired with other redox couples to form novel flow batteries (FBs). As an anolyte, the V(II)/V(III) redox couple can be paired with iron, manganese, cobalt, and cerium redox couples to form novel vanadium-iron (V-Fe), vanadium-manganese (V-Mn), vanadium-cobalt (V-Co), and vanadium-cerium (V-Ce) FBs, respectively. The V(IV)/V(V) redox couple as a catholyte can be coupled with hydrogen to form a vanadium hydrogen (V-H2) FB. In those new redox chemistries, redox reactions, energy density, round-trip efficiencies, crossover issues, and cell components (i.e., separator, ion exchange membrane, and electrode) are different from an all-vanadium flow battery discussed in previous chapters, and thus warrant a detailed discussion.

Vanadium, V-Fe, V-Ce, V-Co↗
DOE OSTI2025

Electrostatic limits on charge selectivity in ultrahigh charge density polymer membranes

Ion-exchange membranes (IEMs) with ultrahigh charge densities offer the promise of enhanced ion transport for electrochemical technologies, yet the fundamental limits of this membrane design strategy are not yet understood. In this work, we present a systematic study of bis(1-vinyl-3-imidazolium) cross-linked polymer membranes with fixed charge contents ranging from 6 to 9 mol/L[dry polymer], synthesized to isolate the effects of charge density at constant membrane water content. While ionic conductivity increases monotonically with increasing charge density, a sharp decline in charge selectivity is observed for the most densely charged membranes, defying conventional expectations. Structural, thermal, and mechanical analyses reveal a critical onset of network disruption and anomalous ion partitioning behavior in these densely charged membranes. With proper consideration of cross-linker geometry, these results are interpreted using Manning's counter-ion condensation theory, which suggests that closely packed charged cross-linkers amplify inter-chain electrostatic interactions and trigger excess counter-ion condensation. Our findings suggest that, beyond a threshold spacing between fixed charges, increased functionalization may harm rather than help charge selectivity of IEMs.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Probing local electrochemistry via mechanical cyclic voltammetry curves

Understanding the mechanical response of an electrode during electrochemical cycling and its correlation to the device electrochemical performance is crucial to improving the performance of insertion-type energy storage devices, electrochemical actuators, water purification, ion separation and neuromorphic computing applications. Here, we visualized the electro-chemo-mechanical coupling behaviors during charge storage of anhydrous and hydrated WO 3 electrodes via in situ atomic force microscopy (AFM) and developed the concept of mechanical cyclic voltammetry (mCV) curves. The relationship between electrochemical current and strain was investigated with simplified models and the results revealed that the proton insertion/deinsertion process could be described through potential-dependent electro-chemo-mechanical coupling coefficients which might indicate changes in insertion processes during electrode cycling. The mCV mapping results highlight the local heterogeneity and show that the charging processes varied across the electrode. These local variations could be further correlated to local morphology, crystal orientations or chemical compositions with proper electrode designs.

36 MATERIALS SCIENCE↗
DOE OSTI2021

New approach to precisely measure γ-ray intensities for long-lived fission products, with results for the decay of 95 Zr

For many fission products, the rays emitted following decay provide an easily-detectable signature that can be used to identify their quantities and distributions in a sample. As a result, γ-ray spectroscopy is often exploited to study fission-product yields, provided sufficiently accurate information on the γ-ray intensity is available. However, in many cases, the uncertainties in the existing nuclear data are large enough that they compromise the precision achievable for modern experiments and applications. To address this need, we have developed a new experimental method that is well suited to precisely measure absolute γ-ray intensities in the β decay of long-lived fission products. The approach involves the production of a radiopure sample by implantation of a mass-separated ion beam from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) facility on a thin carbon foil. The emitted β-decay radiation is detected with a 4π gas proportional counter and a meticulously efficiency-calibrated high-purity germanium (HPGe) detector. As a first measurement to demonstrate the approach, we studied the absolute γ-ray intensities of the strongest transitions following the β decay of 95 Zr and its decay-daughter 95 Nb, and determined them to fractional precisions of better than 1–2%. In addition, with a larger sample of activity produced through neutron irradiation of an isotopically-enriched Zr foil, we performed a high-precision measurement of the relative γ-ray intensities following the decay of 95 Zr with just the HPGe detector. Here, the sample-production method at CARIBU and the coincidence detection approach demonstrated here can be applied to study fission products with half-lives longer than a day, which includes isotopes important not only for nuclear-energy and national-security applications, but also for medical-isotope research and environmental monitoring.

4π↗
DOE OSTI2023

Calcium Cosalt Addition to Alter the Cation Solvation Structure and Enhance the Ca Metal Anode Performance

Accessing the energy density and sustainability of calcium metal batteries requires mastering reversible calcium electrodeposition through electrolyte design. Several electrolytes support reversible, ambient temperature deposition but at utilization and rate too low for practical applications. These challenges stem from solvation structures characterized by either high barriers for cation desolvation or thermodynamic instability, leading to parasitic decomposition of the salt and solvent. The optimal solvation structure for the effective delivery of calcium to the electrode interface is not known. In this work, we show that adding a relatively small amount of a weakly associating calcium salt (calcium carba-closo-dodecaborate) to an otherwise strongly associated solution (calcium borohydride in tetrahydrofuran) produces a surprising population of fully solvent-coordinated Ca2+ cations in the form of solvent-separated ion pairs (SSIPs). We further demonstrate that the formation of these SSIPs beneficially impacts the kinetics and thermodynamics of calcium electrodeposition, revealing the unexpected finding that direct coordination of Ca2+ by the BH4– anion limits the electrodeposition process. These findings reveal how the competition between solvent and anion coordination to Ca2+ affects calcium deposition kinetics and cycling stability, setting the stage for a new calcium electrolyte design based on mixed anion electrolytes.

Landers, Alan T.↗
DOE OSTI2023

Tris(carbene)borates; alternatives to cyclopentadienyls in organolanthanide chemistry

The chemistry of the tris-carbene anion phenyltris(3-alkyl-imidazoline-2-yliden-1-yl)borate, [C3 Me ] - ligand, is initiated for f-block metal cations. Neutral, molecular complexes of the form Ln(C3) 2 I are formed for cerium(III), while a separated ion pair [Ln(C3) 2 ]I forms for ytterbium(III). DFT/QTAIM computational analyses of the complexes and related tridentate tris(pyrazolyl)borate (Tp) – supported analogs demonstrates the anticipated strength of the σ donation and confirms greater covalency in the metal–carbon bonds of the [C3 Me ] - complexes in comparison with those in the Tp Me,Me complexes. The DFT calculations demonstrate the crucial role of THF solvent in accurately reproducing the contrasting molecular and ion-pair geometries observed experimentally for the Ce and Yb complexes.

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

Exploring the use of the pentaphenylcyclopentadienyl ligand in uranium chemistry: the crystal structure of (C

The reaction of UI3 with NaC5Ph5 in THF generated (η5-C5Ph5)UI2(THF)2 which was characterized by X-ray crystallography. The complex has a four-legged piano stool structure with a 2.539 Å U– (C5Ph5 ring centroid) distance that is slightly longer than the 2.504 Å distance in (η5-C5Me5)UI2(THF)3 which has a larger formal coordination number. Although the synthesis of the mono-cyclopentadienyl complex was facile, no bis-cyclopentadienyl complexes were isolated from reactions using two equivalents of the pentaphenylcyclopentadienyl ligand per uranium. In one UI3/2NaC5Ph5 synthesis, the X-ray crystal structure of (THF)3Na(η5-C5Ph5) was obtained. Attempts to reduce (η5-C5Ph5)UI2(THF)2 did not give evidence for a UII product. KC8 reductions of the in situ reaction of NdI3 and NaC5Ph5, analogous to the synthesis of (η5-C5Ph5)UI2(THF)2, yielded an X-ray crystal structure of a solvent-separated ion pair (SSIP), [K(18-crown-6)(THF)2][C5Ph5].

Chemistry↗
DOE OSTI2022

Trivalent ion overcharging on electrified graphene

We report the structure of the electrical double layer (EDL) formed near graphene in aqueous environments strongly impacts its performance for a plethora of applications, including capacitive deionization. In particular, adsorption and organization of multivalent counterions near the graphene interface can promote nonclassical behaviors of EDL including overcharging followed by co-ion adsorption. In this paper, we characterize the EDL formed near an electrified graphene interface in dilute aqueous YCl 3 solution using in situ high resolution x-ray reflectivity (also known as crystal truncation rod) and resonant anomalous x-ray reflectivity (RAXR). These interface-specific techniques reveal the electron density profiles with molecular-scale resolution. We find that yttrium ions (Y 3+ ) readily adsorb to the negatively charged graphene surface to form an extended ion profile. This ion distribution resembles a classical diffuse layer but with a significantly high ion coverage, i.e., 1 Y 3+ per 11.4 ± 1.6 Å 2 , compared to the value calculated from the capacitance measured by cyclic voltammetry (1 Y 3+ per ~240 Å 2 ). Such overcharging can be explained by co-adsorption of chloride that effectively screens the excess positive charge. The adsorbed Y 3+ profile also shows a molecular-scale gap (≥ 5 Å) from the top graphene surfaces, which is attributed to the presence of intervening water molecules between the adsorbents and adsorbates as well as the lack of inner-sphere surface complexation on chemically inert graphene. We also demonstrate controlled adsorption by varying the applied potential and reveal consistent Y 3+ ion position with respect to the surface and increasing cation coverage with increasing the magnitude of the negative potential. This is the first experimental description of a model graphene-aqueous system with controlled potential and provides important insights into the application of graphene-based systems for enhanced and selective ion separations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Discrete ion stochastic continuum overdamped solvent algorithm for modeling electrolytes

In this paper we develop a methodology for the mesoscale simulation of strong electrolytes. The methodology is an extension of the fluctuating immersed-boundary approach that treats a solute as discrete Lagrangian particles that interact with Eulerian hydrodynamic and electrostatic fields. In both algorithms the immersed-boundary method of Peskin is used for particle-field coupling. Hydrodynamic interactions are taken to be overdamped, with thermal noise incorporated using the fluctuating Stokes equation, including a "dry diffusion" Brownian motion to account for scales not resolved by the coarse-grained model of the solvent. Long-range electrostatic interactions are computed by solving the Poisson equation, with short-range corrections included using an immersed-boundary variant of the classical particle-particle particle-mesh technique. Also included is a short-range repulsive force based on the Weeks-Chandler-Andersen potential. This methodology is validated by comparison to Debye-Hückel theory for ion-ion pair correlation functions, and Debye-Hückel-Onsager theory for conductivity, including the Wien effect for strong electric fields. In each case, good agreement is observed, provided that hydrodynamic interactions at the typical ion-ion separation are resolved by the fluid grid.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Mechanochemically accelerated deconstruction of chemically recyclable plastics

Plastics redesign for circularity has primarily focused on monomer chemistries enabling faster deconstruction rates concomitant with high monomer yields. Yet, during deconstruction, polymer chains interact with their reaction medium, which remains underexplored in polymer reactivity. Here, we show that, when plastics are deconstructed in reaction media that promote swelling, initial rates are accelerated by over sixfold beyond those in small-molecule analogs. This unexpected acceleration is primarily tied to mechanochemical activation of strained polymer chains; however, changes in the activity of water under polymer confinement and bond activation in solvent-separated ion pairs are also important. Together, deconstruction times can be shortened by seven times by codesigning plastics and their deconstruction processes.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Facility upgrade for superheavy-element research at RIKEN

The RIKEN Nishina Center (RNC) executed an accelerator upgrade project for the heavy-ion linac (called RILAC). A superconducting RIKEN linear accelerator (SRILAC) and a new superconducting electron-cyclotron-resonance ion source (SC-ECRIS) to boost the final energy and intensity were constructed, aimed at synthesizing a new superheavy element, 119, through a hot fusion reaction. The project included the construction of a gas-filled recoil ion separator (GARIS-III) suitable for detecting the residues of the hot-fusion reaction. To avoid research interruption during the SRILAC construction period (2017–2019) and gain experience in hot-fusion reaction processes, GARIS-II located in the GARIS experimental hall in LINAC building was moved to the E6 experimental hall in Nishina building. Certain exploratory measurements were performed employing the beams accelerated by RILAC2 and the RIKEN ring cyclotron (RRC), which is a part of the existing accelerator complex of the radioactive isotope beam factory (RIBF). Further, commissioning experiments with the upgraded facility (SRILAC and GARIS-III) were performed. The upgrade project and its commissioning results are chronologically described in this article.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Electrolyte Solvation and Ionic Association. VII. Correlating Raman Spectroscopic Data with Solvate Species

Raman spectroscopy is a widely utilized method for determining information about the solvate species present in electrolyte solutions. Difficulties arise, however, when interpreting the Raman data in terms of correlating the spectroscopic vibrational bands with specific solvate species. Examples are provided to demonstrate how erroneous conclusions may be drawn with regard to the identity and population (distribution) of the solvent-separated ion pair (SSIP), contact ion pair (CIP) and aggregate (AGG) solvate species frequently mentioned in the scientific literature.

contact ion pairs↗
DOE OSTI2021

Hydrogen isotope fractionation using graphene and related 2-D materials. Final report

This report provides a final technical report and listing of products from the research on a research project from Clemson university, focused on use of two-dimensional materials within membranes to accomplish hydrogen ion separations. The project used CVD graphene and related 2D materials to accomplish hydrogen / deuterium / tritium (H/D/T) separation during water electrolysis in proton-exchange-membrane (PEM)-style cells. 2D materials were incorporated into PEM cells at varying places with the aim of accomplishing isotopic sieving through 2D materials by selective hydron transport at high rates and with high selectivity. The project work scope included studies on H/D separation with small-scale cells at Clemson, collaborative work between Clemson and SRNL on computational modeling and tritium separations, and issues associated with scaleup.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2024

Intermediate Scale Test Platform Conceptual Design and Hybrid Resin Performance Evaluation Recommendations

Recent laboratory evaluations demonstrated that further testing of alternative hybrid resins is warranted for their potential use as part of the 200 West Area (200W) pump-and-treat (P&T) remedy. 200W P&T has been treating technetium (Tc) since 2012 and uranium (U) since 2015 via two separate ion exchange (IX) treatment units: a single treatment train (i.e., a three-vessel system) for the removal of uranium utilizing a gel strong base anion (SBA) exchange resin, Dowex 21K; and two parallel treatment trains for the removal technetium using a gel SBA resin, Purolite® A532E. While these resins have been removing these contaminants effectively, new hybrid resins can provide additional benefits of further optimizing the IX treatment unit capacities and addressing additional treatment needs (e.g., Cr(VI)) by removing multiple contaminants simultaneously and/or through specific design configurations. Some of these resins also demonstrated some level of removal for I-129 which would be significant for expansion of the P&T into the 200 East Area. This document provides design recommendations for an intermediate scale test platform (ISTP) to evaluate alternative hybrid IX resin performance under conditions approaching field scale and using 200W P&T process groundwater. Results from the ISTP will provide the technical basis required to inform alternative IX resin selection in future 200W P&T facility operations where the treatment of multiple contaminants of concern may be required.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Probing Optimal Reaction Energy for Synthesis of Element 119 from 51 V+ 248 Cm Reaction with Quasielastic Barrier Distribution Measurement

Here, the quasielastic barrier distribution of 51 V+ 248 Cm was extracted by measuring the excitation function of quasielastic backscattering using a gas-filled recoil ion separator, GARIS-III. The obtained barrier distribution is well explained by the coupled-channels calculation, indicating a significant effect of the rotational excitation of deformed 248 Cm. From the measured average Coulomb barrier height and deformation parameters of 248 Cm, the side-collision energy leading to a compact configuration of colliding nuclei was obtained. The relation between the side collision energy and the excitation function of the evaporation-residue cross sections in the 48 Ca+ 248 Cm system was evaluated as a reference for the 51 V+ 248 Cm case. The optimal reaction energy to synthesize a new element 119 at the 51 V+ 248 Cm fusion reaction (3n and 4n channels) was estimated with an aid of these experimental data.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗