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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 1,333 records · Page 74
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

3D Printing of Highly Porous Polypropylene Separators for Lithium‐Ion Batteries Using Fused Deposition Modeling and Thermally Induced Phase Separation

Appearing as one of the key-components of lithium-ion batteries (LIBs), this work specifically focuses on the additive manufacturing (AM) of custom-shape separators, facilitated by the filament material extrusion process, also called fused deposition modeling (FDM). The development and optimization of composite thermoplastic filament feedstocks combining polypropylene and paraffin wax, followed by the 3D printing of the separator membranes is shown. A post-processing step, based on thermal induced phase separation (TIPS), is introduced to promote porosity formation through removal of the paraffin wax sacrificial phase within the 3D printed items. Separators with different polypropylene/paraffin wax ratios are developed and the impact on printability, mechanical strength, porosity, and electrochemical performances, is thoroughly discussed. X-ray micro-computed tomography is employed to assess the geometric fidelity and to detect printing defects in a complex 3D lattice structure. The performance of the 3D printed porous separators is also compared to a commercial separator. This pioneering research establishes a foundation for the creation of porous separators that can adapt to and conform into 3D printed battery architectures with novel form factors, and also creates opportunities for the use of FDM and TIPS for a wide range of applications that employ porous structures beyond the energy storage field.

3D printing↗
DOE OSTI2017

Bioderived Muconates by Cross-Metathesis and Their Conversion into Terephthalates

Polyethylene terephthalate that is 100 % bioderived is in great demand in the market guided by the ever-more exigent sustainability regulations with the challenge of producing renewable terephthalic acid remaining. Renewable terephthalic acid or its precursors can be obtained by Diels–Alder cycloaddition and further dehydrogenation of biomass-derived muconic acid. The cis,cis isomer of the dicarboxylic acid is typically synthesized by fermentation with genetically modified microorganisms, a process that requires complex separations to obtain a high yield of the pure product. Moreover, the cis isomer has to be transformed into the trans,trans form and has to be esterified before it is suitable for terephthalate synthesis. To overcome these challenges, we investigated the synthesis of dialkyl muconates by cross-metathesis. The Ru-catalyzed cross-coupling of sorbates with acrylates, which can be bioderived, proceeded selectively to yield diester muconates in up to 41 % yield by using very low catalyst amounts (0.5–3.0 mol %) and no solvent. In the optimized procedure, the muconate precipitated as a solid and was easily recovered from the reaction medium. Analysis by GC–MS and NMR spectroscopy showed that this method delivered exclusively the trans,trans isomer of dimethyl muconate. The Diels–Alder reaction of dimethyl muconate with ethylene was studied in various solvents to obtain 1,4-bis(carbomethoxy)cyclohexene. The cycloaddition proceeded with very high conversions (77–100 %) and yields (70–98 %) in all of the solvents investigated, and methanol and tetrahydrofuran were the best choices. Next, the aromatization of 1,4-bis(carbomethoxy)cyclohexene to dimethyl terephthalate over a Pd/C catalyst resulted in up to 70 % yield in tetrahydrofuran under an air atmosphere. Because of the high yield of the reaction of dimethyl muconate to 1,4-bis(carbomethoxy)cyclohexene, no separation step was needed before the aromatization. This is the first time that cross-metathesis is used to produce bioderived trans,trans-muconates as precursors to renewable terephthalates, important building blocks in the polymer industry.

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

Understanding ZIF-8 Performance upon Gas Adsorption by Means of Inelastic Neutron Scattering

We present that despite the vast number of publication dealing with ZIF-8, the performance of this zeolitic MOF upon adsorption is still a matter of debate. The understanding of its adsorption properties its of great importance to define its potential in aplications such as gas separation, sensing and catalytic processes. Using inelastic neutron scattering (INS) upon exposure to different probe molecules we get further insight about the adsortion performance at cryogenic temperatures, including the possible swinging of the imidazolate linkers.

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

Search for new phenomena in final states with large jet multiplicities and missing transverse momentum using $\sqrt{s}$ = 13 TeV proton-proton collisions recorded by ATLAS in Run 2 of the LHC

Results of a search for new particles decaying into eight or more jets and moderate missing transverse momentum are presented. The analysis uses 139 fb - 1 of proton-proton collision data at s = 13 TeV collected by the ATLAS experiment at the Large Hadron Collider between 2015 and 2018. The selection rejects events containing isolated electrons or muons, and makes requirements according to the number of b -tagged jets and the scalar sum of masses of large-radius jets. The search extends previous analyses both in using a larger dataset and by employing improved jet and missing transverse momentum reconstruction methods which more cleanly separate signal from background processes. No evidence for physics beyond the Standard Model is found. The results are interpreted in the context of supersymmetry-inspired simplified models, significantly extending the limits on the gluino mass in those models. In particular, limits on the gluino mass are set at 2 TeV when the lightest neutralino is nearly massless in a model assuming a two-step cascade decay via the lightest chargino and second-lightest neutralino.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

The Effects of Sc Addition on the Microstructure and Mechanical Properties of Be-Al Alloy Fabricated by Induction Melting

This study investigated the alloying effects of 0.4 wt.% Sc on the microstructure, mechanical properties, and fracture behavior of a cast Be-Al alloy prepared by vacuum induction melting. The micromechanics of Sc-containing secondary-phase particles (SPs) were characterized by nanoindentation, and the fracture behavior of the alloy was investigated via tensile fractography and optical metallography. The addition of 0.4 wt.% Sc significantly modified the alloy microstructure by decreasing the secondary dendritic arm spacing (SDAS), weakening the dendritic structure of Be, and producing an equiaxed/cellular alloy microstructure with refined Be grains. Sc alloying increased the Vickers hardness by 36%, elastic modulus by 28%, yield strength by 35%, ultimate strength by 52%, but decreased the elongation from 3.6 to 2.9%. Sc-containing SPs had a higher elastic modulus, yield strength, microhardness, and a lower plasticity index than the Be and Al matrices, resulting in interface separation during the fracture process. SPs located at the Be/Al interfaces did not act as microcrack sources for the matrices, whereas highly faceted SPs within the Be grains induced microcrack formation and decreased the elongation. The failure mode of the cast Be-Al-0.4Sc alloy still involved the brittle cleavage failure of Be regions and ductile dimple failure of Al regions, which was not the case with the cast Be-Al alloy.

36 MATERIALS SCIENCE↗
DOE OSTI2019

On the Competition Between Electron Autodetachment and Dissociation of Molecular Anions

We treat the competition between autodetachment of electrons and unimolecular dissociation of excited molecular anions as a rigid-/loose-activated complex multichannel reaction system. To start, the temperature and pressure dependences under thermal excitation conditions are represented in terms of falloff curves of separated single-channel processes within the framework of unimolecular reaction kinetics. Channel couplings, caused by collisional energy transfer and “rotational channel switching” due to angular momentum effects, are introduced afterward. The importance of angular momentum considerations is stressed in addition to the usual energy treatment. Non-thermal excitation conditions, such as typical for chemical activation and complex-forming bimolecular reactions, are considered as well. The dynamics of excited SF{sub 6}{sup −} anions serves as the principal example. Other anions such as CF{sub 3}{sup −} and POCl{sub 3}{sup −} are also discussed. .

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2024

Group hexavalent actinide separation from lanthanides using sodium bismuthate chromatography

Advanced used nuclear fuel (UNF) reprocessing strategies are limited by the complex radiochemical separations and engineering required to achieve the separation of actinides (An) from neutron scavenging lanthanides (Ln). The accessibility of the hexavalent oxidation state for the actinides (U – Am) provides a pathway to achieving a group hexavalent actinide separation from the trivalent lanthanides and Cm. The solid oxidant and ion exchanger, sodium bismuthate (NaBiO 3 ), has been demonstrated to quantitatively oxidize and separate Am from trivalent Cm in a column chromatographic system. This work expands on the use of NaBiO 3 chromatography to characterize the adsorption, kinetic, and elution behavior of U, Pu, and Eu. Separation factors over 200 with rapid kinetics were observed at dilute nitric acid concentrations with a complete An/Ln separation achieved in under an hour. In conclusion, the adsorption and chromatographic behavior of key fission products present in various reprocessing raffinates was characterized which demonstrated potential application of a NaBiO 3 -based separation following a TRUEX process.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2020

Integration of graphical approaches into optimization-based design of multistage liquid extraction

We propose two optimization models for designing two liquid extraction systems: simple multistage liquid extractors and extractors with extract reflux. Both models are motivated by the concepts of the modified McCabe-Thiele graphical method for multistage extractor design. The operating and equilibrium curves in the McCabe-Thiele method are represented by material balances and piece-wise linearized thermodynamics properties. The use of piece-wise approximations improves computational tractability of both optimization models. In addition, we consider some extensions such as dilute systems, insoluble solvents, and non-ideal stages. In conclusion, the applicability of the proposed models is demonstrated with four illustrative examples.

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

Effect of single atom Platinum (Pt) doping and facet dependent on the electronic structure and light absorption of Lanthanum Titanium Oxide (La 2 Ti 2 O 7 ): A Density Functional Theory study

Charge generation and separation are two key processes for semiconductor photocatalysis. Here, we use Pt as a single atom catalyst to systematically examine the facet-dependent electronic band structure and light absorption of the layered perovskite-type wide-gap semiconductor, lanthanum titanium oxide (La 2 Ti 2 O 7 , LTO) by means of density functional theory simulations. In this study, it is found that single Pt atom doping of different LTO surfaces (here, (100), (101) and (001)) can not only create states in the bandgap that would promote the formation of recombination centers, but also shift the optical absorption edge to the visible region. Interestingly, the Pt doping forms a heterojunction, with the valence band maximum consisting of Pt states and the conduction band minimum consisting of LTO states, respectively. To study the facet dependent surface activity, acetic acid (CH 3 COOH) was used as a model molecule to investigate the adsorption and charge transfer on the (101), (100) and (001) Pt-LTO surface facets. The results show that the (101) facet could enable stronger adsorption of CH 3 COOH by promoting more electron transfer during the interfacial interaction. Our theoretical findings aim to promote the design and optimization of the single atom catalysts (SACs) for photocatalytic applications and other broad catalysis systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

In Situ, Time-Resolved, and Mechanistic Studies of Metal–Organic Framework Nucleation and Growth

The vast chemical and structural diversity of metal–organic frameworks (MOFs) opens up the exciting possibility of “crystal engineering” MOFs tailored for particular catalytic or separation applications. Yet the process of reaction discovery, optimization, and scale-up of MOF synthesis remains extremely challenging, presenting significant obstacles to the synthetic realization of many otherwise promising MOF structures. Recently, significant new insights into the fundamental processes governing MOF nucleation and growth, as well as the relationship between reaction parameters and synthetic outcome, have been derived using powerful in situ, time-resolved and/or mechanistic studies of MOF crystallization. This Review provides a summary and associated critical analysis of the results of these and other related “direct” studies of MOF nucleation and growth, with a particular emphasis on the recent advances in instrument technologies that have enabled such studies and on the major hypotheses, theories, and models that have been used to explain MOF formation. We conclude with a summary of the major insights that have been gained from the work summarized in this Review, outlining our own perspective on potential fruitful new directions for investigation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Pretreatment of Biomass by Selected Type-III Deep Eutectic Solvents and Evaluation of the Pretreatment Effects on Hydrothermal Carbonization

Hydrothermal carbonization (HTC) is a novel thermochemical conversion that converts wet biomass into energy dense solid fuel. Residual moisture under subcritical conditions reacts with a lignin-cellulose-hemicellulose matrix with the major reactions being identified as dehydration and decarboxylation. Among other reaction parameters (e.g., temperature, time, pressure), biomass morphology often plays a key role in HTC. The hypothesis of this study was enhancing the porous structure of biomass without significantly affecting biopolymer composition would augment hydrothermal carbonization (HTC). To prove the hypothesis, two type-III deep eutectic solvents (DESs), namely choline chloride:urea (ChCl:Urea, 1:2 mol/mol) and methyltriphenylphosphonium bromide:ethylene glycol (MTPB:EG, 1:4 mol/mol), were studied to pretreat loblolly pine at room temperature and ambient pressure for 1 h. DES pretreatment shows swelling of the biomass, increasing the surface fiber-to-fiber gap length by 52% and 185% for ChCl:Urea and MPTB:EG pretreatments, respectively. The total pore volume remained intact (2.6 × 10 –3 cm 3 /g), although new small pores evolved, and existing pores were abated with DES pretreatment. Hydrochars prepared from DES pretreated loblolly pine showed a high O/C and H/C ratio resulting in a significant increase of energy content (up to 42%) and a decrease of mass yield (up to 50 wt %), indicating an enhancement of HTC severity due to the alteration of surface morphology by DES. Finally, a preliminary process economics revealed that integrated DES pretreatment-HTC would increase fixed capital investment but decrease the cost of operation and manufacturing than the standalone HTC process.

09 BIOMASS FUELS↗
DOE OSTI2025

Predicting Multicomponent Aqueous Phase Adsorption Equilibria of Organic Acids Using the Generalized Brunauer–Emmett–Teller Isotherm Model

Here, to support process development of adsorptive separation of organic acids, this work presents a thermodynamic modeling methodology to predict multicomponent aqueous phase organic acid adsorption equilibria from single-component adsorption isotherms using the generalized Brunauer–Emmett–Teller isotherm model (gBET). With the organic acid fugacities rigorously accounting for the aqueous phase organic acid solution chemistry and solution nonideality, gBET precisely represents the single-component adsorption isotherms and accurately predicts the binary and ternary mixed-acid adsorption equilibria for the ranges of initial pH (∼3–7), acid concentration (100–400 mmol/L), and temperature (298.15–328.15 K) with less than 10% average absolute relative deviation. In addition, gBET with pH-independent parameters provides insights into the underlying adsorption phenomena, including the adsorbate loadings and compositions in the monolayer and subsequent layers under varying initial pH, temperature, concentration, and composition. The gBET model predictions outperform the predictions from the overloading model and the Ideal Dilute Solution Theory.

09 BIOMASS FUELS↗
DOE OSTI2016

Electronic Structure and Dynamics of Higher-Lying Excited States in Light Harvesting Complex 1 from Rhodobacter sphaeroides

Light harvesting in photosynthetic organisms involves efficient transfer of energy from peripheral antenna complexes to core antenna complexes, and ultimately to the reaction center where charge separation drives downstream photosynthetic processes. Antenna complexes contain many strongly coupled chromophores, which complicates analysis of their electronic structure. Two-dimensional electronic spectroscopy (2DES) provides information on energetic coupling and ultrafast energy transfer dynamics, making the technique well suited for the study of photosynthetic antennae. Here in this paper, we present 2DES results on excited state properties and dynamics of a core antenna complex, light harvesting complex 1 (LH1), embedded in the photosynthetic membrane of Rhodobacter sphaeroides . The experiment reveals weakly allowed higher-lying excited states in LH1 at 770 nm, which transfer energy to the strongly allowed states at 875 nm with a lifetime of 40 fs. The presence of higher-lying excited states is in agreement with effective Hamiltonians constructed using parameters from crystal structures and atomic force microscopy (AFM) studies. The energy transfer dynamics between the higher- and lower-lying excited states agree with Redfield theory calculations.

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

Entropy-Driven Porous Liquids Allowing Gas Solubility in Solvent-Filled Imine-Based Porous Organic Cages

Porous liquids offer a promising platform for gas separation by combining fluid processability with intrinsic molecular porosity. Traditional Type II porous liquids are formed by dissolving porous molecular cages in size-excluded solvents, limiting solvent options and practical applications. In this work, we introduce a novel method of creating Type II porous liquids using common small solvents, where intrinsic porosity is achieved at elevated pressures due to the selective displacement of solvent molecules by gas molecules within the cage structures. Using molecular simulations, we investigate the behavior of CO 2 in solutions of the imine-based porous organic cage CC13 dissolved in small molecular solvents such as chloroform and 1,2-dimethoxyethane (DME). Grand canonical Monte Carlo simulations of solid-state CC13 reveal that selectivity reversal, where smaller CO 2 molecules displace larger solvent molecules inside the cage, is achievable at sufficiently high pressures. Temperature quench molecular dynamics simulations confirm that while CO 2 displacement within chloroform-filled cages is limited, DME enables entropy-driven cage CO 2 occupancy at pressures as low as ∼23 bar, setting up the foundation of an alternative way of forming Type II porous liquids.

adsorption↗
DOE OSTI2017

Separating Bulk and Surface Contributions to Electronic Excited-State Processes in Hybrid Mixed Perovskite Thin Films via Multimodal All-Optical Imaging

A comprehensive understanding of electronic excited-state phenomena underlying the impressive performance of solution-processed hybrid halide perovskite solar cells requires access to both spatially resolved electronic processes and corresponding sample morphological characteristics. In this paper, we demonstrate an all-optical multimodal imaging approach that enables us to obtain both electronic excited-state and morphological information on a single optical microscope platform with simultaneous high temporal and spatial resolution. Specifically, images were acquired for the same region of interest in thin films of chloride containing mixed lead halide perovskites (CH 3 NH 3 PbI 3–x Cl x ) using femtosecond transient absorption, time-integrated photoluminescence, confocal reflectance, and transmission microscopies. Comprehensive image analysis revealed the presence of surface- and bulk-dominated contributions to the various images, which describe either spatially dependent electronic excited-state properties or morphological variations across the probed region of the thin films. Finally, these results show that PL probes effectively the species near or at the film surface.

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

Characterizing Hydrated Polymers via Dielectric Relaxation Spectroscopy: Connecting Relative Permittivity, State of Water, and Salt Transport Properties of Sulfonated Polysulfones

Sulfonated polysulfone is a promising membrane material for separation and energy generation processes that rely on membranes to control the rates of small-molecule (e.g., water and ions) transport. The interactions among water molecules, ions, and the sulfonate groups in these polymers play a key role in controlling these rates of transport, but much remains unknown about these fundamental interactions in sulfonated polymers. In this study, we used dielectric relaxation spectroscopy to characterize water molecule dynamics in sulfonated polysulfone and Nafion. We found that the charged sulfonate groups contribute to a restriction of water molecule dynamics (i.e., a reduction in the characteristic time scale of dipolar motions) in a manner that is governed by the concentration and nature (i.e., conjugate base strength) of the sulfonate group. Additionally, we develop strategies to use these data to aid in modeling ion transport in sulfonated polysulfone. These results may be useful to guide engineering strategies for polymeric membranes.

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

Microfluidic, One-Batch Synthesis of Pd Nanocrystals on N-Doped Carbon in Surfactant-Free Deep Eutectic Solvents for Formic Acid Electrochemical Oxidation

One of the grand challenges that impedes practical applications of nanomaterials is the lack of robust manufacturing methods that are scalable, cheap, and environmentally friendly. In this work, we address this challenge by developing a microfluidic approach that produces surfactant-free Pd nanocrystals (NCs) uniformly loaded on N-doped porous carbon in a one-batch process. The deep eutectic solvent (DES) prepared from choline chloride and ethylene glycol was employed as a novel synthesis solvent, and its extended hydrogen networks and abundant ionic species effectively stabilize Pd facets and confine nanocrystal sizes without using surfactants. The microreactors provide faster heat exchange and more uniform mass transport, which in combination with DES produced Pd NCs with better-defined shape and predominately exposed Pd (100) facet. Furthermore, we describe that the N-doped functional groups in porous carbon direct dense and uniform heterogeneous growth of Pd NCs in a one-batch process, thereby eliminating a separate catalyst deposition step that is often involved in conventional synthesis. The Pd NCs in the one-batch-produced Pd/C catalysts exhibited a size distribution of similar to ~13 ± 3.5 nm and a high ESCA of 46.0 m 2 /g and delivered 362 mA/mg for formic acid electrochemical oxidation with improved stability, demonstrating the unique potentials of microfluidic reactors and DES for the controllable and scalable synthesis of electrocatalyst materials for practical applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Influence of the Anionic Zinc-Adeninate Metal–Organic Framework Structure on the Luminescent Detection of Rare Earth Ions in Aqueous Streams

Rare earth elements (REEs) are critical to numerous technologies; however, a combination of increasing demand, environmental concerns, and monopolistic marketplace conditions has spurred interest in boosting the domestic REE production from sources such as coal utilization byproducts. The economic viability of this approach requires rapid, inexpensive, and sensitive analytical techniques capable of characterizing the REE content during resource exploration and downstream REE processing (e.g., analyzing REE separation, concentration, and purification production steps). Luminescence-based sensors are attractive because many REEs may be sensitized to produce element-specific emission. Hence, a single material may simultaneously detect and distinguish multiple REEs. Metal–organic frameworks (MOFs) can sensitize multiple REEs, but their viability has been hindered by sensitivity and selectivity challenges. Understanding how the MOF structure impacts the REE sensing efficacy is critical to the rational design of new sensors. Here, we evaluate the sensing performance of seven different anionic zinc-adeninate MOFs with different organic linkers and/or structures for the visible-emitting REEs Tb, Dy, Sm, and Eu. The choice of a linker determines which REEs are sensitized and significantly influences their sensitivity and selectivity against competing species (here, Fe(II) and HCl). For a given linker, structural changes to the MOF can further fine-tune the performance. The MOFs produce some of the lowest detection limits (sub-10 ppb for Tb) reported for the aqueous sensitization-based REE detection. Importantly, the most selective MOFs demonstrated the ability to sensitize the REE signal at sub-ppm levels in a REE-spiked acid mine drainage matrix, highlighting their potential for use in real-world sensing applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗