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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Lithium purification from aqueous solutions using bioinspired redox-active melanin membranes

The separation of lithium from magnesium ions in salt brines is an important step in producing raw lithium for prospective use in electrochemical storage systems. Liquid–liquid extraction of Mg 2+ ions from Li + ions is challenging because of comparable thermodynamic behavior in aqueous solutions. Removing Mg 2+ ions from brines using consumable ion-exchange membranes is also a challenging prospect due to poor chemical selectivity and compromised sustainability. In this work, we propose the use of redox-active catechols in the form of melanin pigments for selective removal of Mg 2+ ions from aqueous solutions. Synthetic melanin films are oxidatively polymerized on stainless steel meshes from aqueous solutions of dopamine precursors to create electrochemically functionalized polydopamine membranes. The binding selectivity of redox-active catechol-bearing polydopamine melanin for Mg 2+ ions in aqueous solutions was measured as a function of electrochemical cycling. The binding kinetics of Mg 2+ ions to polydopamine pigments was measured. Mg 2+ ions binding selectivity to polydopamine in mixed aqueous solutions containing both Li + and Mg 2+ ions were also measured. Additionally, the equilibrium binding concentrations of Mg 2+ ions to polydopamine were achieved very rapidly (<1 min). Finallym, redox-active polydopamine membranes therefore show promise as functional materials for the separation of Mg 2+ and Li + ions in aqueous solutions.

25 ENERGY STORAGE↗
DOE OSTI2020

Tubulin Double Helix: Lateral and Longitudinal Curvature Changes of Tubulin Protofilament

By virtue of their native structures, tubulin dimers are protein building blocks that are naturally pre-programmed to assemble into cytoskeletal polymers known as microtubules (MTs). Here we demonstrate polycation-directed (i.e. electrostatically tunable) assembly of tubulins through tubulin protofilament conformational changes in the longitudinal and lateral directions, creating novel tubulin double helices and various tubular architectures. Synchrotron small angle X-ray scattering and transmission electron microscopy reveal a remarkable range of nanoscale assembly structures: single- and double-layered double-helix tubulin tubules. The phase transitions from MTs into the new assemblies are dependent on the size and concentration of polycations. Two characteristic scales that determine the number of observed phases are the size of polycation compared to the size of tubulin (≈4 nm) and MT diameter (≈25 nm). This work suggests the feasibility of “programmable breakdown” of protein nanotubes, tearing MTs into double-stranded tubulins and building up previously undiscovered nanostructures, by using polycations with scissor- and glue-like properties. Importantly, we define a new role of tubulins as two-dimensionally shape-controllable building blocks for novel supramolecular architectures. Furthermore, these findings provide insight into the design of protein-based functional materials, for example, as metallization templates for nanoscale electronic devices, kinesin motor-driving molecular screws, and anticancer drug delivery vehicles.

2D shape‐control↗
DOE OSTI2023

The Crystal Structure of BaZn 2 Se 2 (OH) 2 Featuring Brownmillerite‐Type Layers

Abstract A bimetallic hydroxychalcogenide, BaZn 2 Se 2 (OH) 2 , was synthesized through hydrothermal pouch methods. The single crystal X‐ray diffraction and electron diffraction indicates that the phase crystallizes in the orthorhombic space group Pnma and is composed of anionic layers [ZnSe 3/3 (OH) 1/1 ] − that are separated and charged balanced by Ba 2+ cations. The [ZnSe 3/3 (OH) 1/1 ] – layer comprises two unique Zn sites, which form interpenetrating zigzag chains with an in‐plane dipole moment and adopts a brownmillerite‐type structural motif. The adjacent layers contain tetrahedrally coordinated Zn chains of opposite handedness related by an inversion center, which cancel the microscopic dipoles to minimize the macroscopic electric polarization. The adoption of a brownmillerite structural motif in BaZn 2 Se 2 (OH) 2 can be rationalized by the distinct charge difference between Se 2− and OH − anions, which creates a sufficient dipole moment in the ZnSe 3 (OH) tetrahedra to allow the occurrence of twisted chains. FTIR spectroscopy confirms the existence of OH − anions and DFT calculations indicate that BaZn 2 Se 2 (OH) 2 is a semiconductor with a direct band gap. This work expands the chemistry of the brownmillerite family from traditional homoanionic oxides to multianion hydroxychalcogenides, offering a new opportunity to explore tunable structural complexity for better design of functional materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Chemomechanics of ionically conductive ceramics for electrical energy conversion and storage

Functional materials for energy conversion and storage show strong coupling between electrochemistry and mechanics. For instance, ceramics developed as electrodes for both solid oxide fuel cells and batteries exhibit cyclic volumetric expansion upon reversible ion transport. Such chemomechanical coupling is typically far from thermodynamic equilibrium, and thus is challenging to quantify experimentally and computationally. In situ measurements and atomistic simulations are under rapid development to explore how this coupling can be used to potentially improve both device performance and durability. In this work, we review the commonalities of coupling between electrochemical and mechanical states in fuel cell and battery materials, illustrating with specific cases the progress in materials processing, in situ characterization, and computational modeling and simulation. We also highlight outstanding questions and opportunities in these applications – both to better understand the limiting mechanisms within the materials and to significantly advance the durability and predictability of device performance required for renewable energy conversion and storage.

25 ENERGY STORAGE↗
DOE OSTI2019

Enrichment and Recovery of Cr(VI) from Aqueous Solution via a Monolithic Loofah Sponge Modified by Tannins and Arginine

In this study, a monolithic loofah sponge (LS) matrix, which was pretreated by hemicellulase and decorated by amino and guanidine, was successfully endowed with two functions: adsorption and recovery for Cr(VI). As an adsorbent, the modified LS (LS–TAA) has a high adsorption capacity (327.91 mg/g) for Cr(VI), and can be handily reused because of its integrity, good mechanical strength and convenient separation from aqueous solution. As a carrier, the residue of Cr-loaded LS–TAA was discovered to be pure Cr{sub 2}O{sub 3} nanoparticles after calcination. The effect of hemicellulase pretreatment and influencing factors, adsorption kinetics, thermodynamics and isotherm adsorption models were investigated. The samples were characterized by various means including SEM, EDX, FT–IR, XRD, XPS and TEM. The results demonstrated that the LS–TAA should be viewed as a low-cost environment functional material with application potential to treat Cr-polluted wastewater. Graphical Abstract: .

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

The Effect of Folic Acid- and Caffeic Acid-Functionalized SPION on Different Cancer Cell Lines

In this study, caffeic acid (CFA)- and folic acid (FA)-conjugated superparamagnetic iron oxide bio-nanocomposite (SPION@PEG-FA-@CFA) was prepared and its cytotoxic and apoptotic effects against murine fibroblast (L929), glioblastoma (U87), adenocarcinoma, human breast cancer (MCF-7), epithelioid cervix carcinoma (HeLa), and lung carcinoma (A549) have been determined. A real-time cell analyzer system (RTCA) for cytotoxicity, annexin assay and TUNEL, caspase 3/7 expression level, and caspase 3/7 activities for apoptosis were used. The RTCA showed that the cytotoxic effects of the bio-nanocomposite were higher in U87, MCF-7, and HeLa cells (which are folic acid-positive cells (FAR (+))). TUNEL, annexin, and caspase assay results indicated that the bio-nanocomposite caused apoptotic and necrotic impacts on cells. Necrotic and apoptotic cell ratios in FAR-positive cells (L929 and A549) were lesser than those in U87, MCF-7, and HeLa cells (FAR (+)). Therefore, the obtained results showed that the bio-nanocomposite can be used as a nano-medicine for biomedical application (cancer treatments). Moreover, this work can also be useful for designing other functionalized materials which could act as biomaterial. This study will be also informative for the researchers to design novel materials for biomedical applications.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

From lithium-ion to sodium-ion battery

The review discusses the problems of development of sodium-ion batteries intended to replace lithium-ion batteries used in large power plants (electric transport, smart grids). The literature data, mainly for the last five years, devoted to electrode functional materials and electrolytes used in sodium-ion batteries are presented and analyzed.

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

Pressure-induced cation and vacancy disorder-order transition and near-zero τ f in deficient hexagonal perovskite Ba 8 ZnTa 6 O 24 dielectrics

Pressure applications can enable the tuning of atomic/defect ordering and provide access to new functional materials. Here, in this study, we report that pressure-induced structural transformation featuring disorder-order transition of both cations and vacancies in the 8-layer deficient hexagonal perovskite tantalate dielectrics Ba 8 ZnTa 6 O 24 , which transformed the structure from twin to shift and remarkably lowered the temperature coefficient of resonant frequency τ f down to near zero (∼0.56 ppm/°C) from 38 ppm/°C for the twinned precursor. The atomic scale STEM-HAADF and EDS results confirm the ordering of Zn in the Ta host at the nanometer scale in the shifted material featuring well-ordered Ba 8 ZnTa 6 O 24 slabs intergrown with Ba 3 ZnTa 2 O 9 and Ba 5 Ta 4 O 15 monolayers and anti-phase grain boundaries as planar defects. The pressure-induced twin-shift structural transformation of Ba 8 ZnTa 6 O 24 features the rare constant concentration of the hexagonal stacked layers, which is allowed by the vacancy ordering at the central layers of face-shared octahedral (FSO) trimers avoiding the FSO B-B repulsion, and remarkably the faster cationic ordering kinetics compared with the 2:1 ordered complex perovskites. Although the inclusion of numerous planar defects and the oxidizable atomic defects led to significant p-type conduction and inhomogeneous electrical microstructures, resulting in an extraordinarily high extrinsic dielectric loss for the high-pressure shifted Ba 8 ZnTa 6 O 24 pellet, the intrinsically near-zero τ f could make the shifted Ba 8 ZnTa 6 O 24 perovskite an ideal microwave dielectric resonator candidate if the defects could be eliminated.

high pressure↗
DOE OSTI2020

Fundamental Phenomena and Applications of Swift Heavy Ion Irradiations

This review concentrates on the specific properties and characteristics of damage structures generated with high-energy ions in the electronic energy loss regime. Irradiation experiments with so-called swift heavy ions (SHIs) find applications in many different fields, with examples presented in ion-track nanotechnology, radiation hardness analysis of functional materials, and laboratory tests of cosmic radiation. The basics of the SHI-solid interaction are described with special attention to processes in the electronic subsystem. The broad spectrum of damage phenomena is exemplified for various materials and material classes, along with a description of typical characterization techniques. This review also presents state-of-the-art modeling efforts that try to account for the complexity of the coupled processes of the electronic and atomic subsystems. Lastly, a brief discussion at the end of this review on SHI phenomena induced by fission fragments in nuclear materials will highlight the relevance of energetic ion irradiation in nuclear technology applications.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Coupled effects of electronic and nuclear energy deposition on damage accumulation in ion-irradiated SiC

Coupling between electronic and nuclear energy dissipation in ion-irradiated, single crystal 4H-SiC has been investigated using Si, Ti, and Ni ions over a range of energies at 300 K, and irradiation damage accumulation is characterized using Rutherford backscattering spectroscopy in channeling geometry. The damage production rate from nuclear energy loss (S n ) is observed to decrease with increasing electronic energy loss (S e ) of the incident ions. A dynamic threshold (S e,th ) in electronic energy loss is determined for each ion species, which defines two regions: i) S e > S e,th , where electronic energy dissipation fully suppresses damage production due to nuclear energy loss along incident ion paths, and ii) S e < S e,th , where simultaneous damage recovery due to Se competes with damage production processes. Here, the electronic energy loss threshold (S e,th ) increases sublinearly with incident ion atomic number. Here, the assessment of S e,th and how it affects damage accumulation is important to advance the understanding of complex processes occurring under ion-solid interactions, as well as in the design of functional materials for opto-electronics and novel structural materials and devices tolerant to harsh thermal and radiation environments.

36 MATERIALS SCIENCE↗
DOE OSTI2022

3D-printed electrically conductive silicon carbide

The development of electrically conductive ceramics could achieve robust mechanical strength as well as practically high conductivity, offering applications in structural electrodes, conductors, catalyst supports, etc. However, its operating temperature is limited due to the intrinsic dense structures inevitably hindering the thermal management capability, thus resulting in a temperature-dependent electrical behavior in high-temperature environments. In this work, we report an additive manufacturing protocol through vat photopolymerization 3D printing to fabricate the architectured conductive silicon carbide (SiC) ceramics that simultaneously possess high electrical conductivity as well as low thermal conductivity, and demonstrate electric reliability under high-temperature environments above 600°C. The percolation of graphene into the ceramic scaffold establishes a uniform conductive network, exhibiting its electrical conductivity up to 1000 S m –1 . The bulk density of the 3D-printed ceramic is measured from 0.366 g cm –3 to 0.897 g cm –3 , with thermal conductivity ranging from 62 mW m –1 K –1 to 88 mW m –1 K –1 . Furthermore, the mechanical performance of conductive ceramic can be effectively reinforced by densifying the microstructures via spark plasma sintering treatment. The proposed additive manufacturing strategy widens the potential of ceramics as a structural and functional material, offering a promising pathway toward high-temperature electronics applications.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Single-unit-cell layer established Bi 2 WO 6 3D hierarchical architectures: Efficient adsorption, photocatalysis and dye-sensitized photoelectrochemical performance

Single-layer catalysis sparks huge interests and gains widespread attention owing to its high activity. Simultaneously, three-dimensional (3D) hierarchical structure can afford large surface area and abundant reactive sites, contributing to high efficiency. Herein, we report an absorbing single-unit-cell layer established Bi2WO6 3D hierarchical architecture fabricated by a sodium dodecyl benzene sulfonate (SDBS)-assisted assembled strategy. The DBS- long chains can adsorb on the (Bi2O2)2+ layers and hence impede stacking of the layers, resulting in the single-unit-cell layer. We also uncovered that SDS with a shorter chain is less effective than SDBS. Due to the sufficient exposure of surface O atoms, single-unit-cell layer 3D Bi2WO6 shows strong selectivity for adsorption on multiform organic dyes with different charges. Remarkably, the single-unit-cell layer 3D Bi2WO6 casts profoundly enhanced photodegradation activity and especially a superior photocatalytic H2 evolution rate, which is 14-fold increase in contrast to the bulk Bi2WO6. Systematic photoelectrochemical characterizations disclose that the substantially elevated carrier density and charge separation efficiency take responsibility for the strengthened photocatalytic performance. Additionally, the possibility of single-unit-cell layer 3D Bi2WO6 as dye-sensitized solar cells (DSSC) has also been attempted and it was manifested to be a promising dye-sensitized photoanode for oxygen evolution reaction (ORR). Our work not only furnish an insight into designing single-layer assembled 3D hierarchical architecture, but also offer a multi-functional material for environmental and energy applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Atomic layer deposition in porous electrodes: A pore-scale modeling study

Coating porous electrodes of Li-ion batteries with functional materials by atomic layer deposition (ALD) can enhance their capacity stability. Because of the complex microstructure of the porous electrodes, predicting the required exposure time of the precursors for achieving a desired coating and the coating characteristics for a given exposure time remains difficult. Here, a three-dimensional (3D) pore-scale lattice Boltzmann model is developed to investigate the reactive transport processes during the ALD of reconstructed electrodes and to assess the accuracy of one-dimensional (1D) mean-field models. The effects of the hierarchical structure of pores and their connectivity on the coating process of ALD are investigated and the detailed coating characteristics in the electrodes are resolved. Electrodes with smaller pore sizes requires a longer exposure time to achieve full coating. At the same depth within an electrode, the smaller pores are coated more slowly than the wider pores (especially at high Damkohler numbers) and the coating speed of well-connected pores are faster than that of poorly connected pores. Furthermore, simulations also reveal that the 1D mean-field model can capture the average coating characteristics reasonably well when pores in the electrodes are well connected but may perform poorly if the pores are poorly connected.

25 ENERGY STORAGE↗
DOE OSTI2018

Effect of doping on the performance of high-crystalline SrMnO 3 perovskite nanofibers as a supercapacitor electrode

Perovskite oxides are promising multi-functional materials with enhanced physical and chemical properties. In this study, high-crystalline SrMnO 3 perovskite oxide nanofibers have been successfully synthesized by sol–gel electrospinning followed by calcination at different temperatures, using polyvinylpyrrolidone as a sacrificial polymeric binder. The change in porosity and grain size with calcination temperature imparted a substantial effect on the electrochemical properties of the obtained SrMnO 3 nanofibers. The SrMnO 3 nanofiber electrode calcined at 700 °C exhibits an electrochemical capacitance of 321.7 F g –1 at a discharge current density of 0.5 A g –1 . Here, the effect of doping Ba/Ca on Sr, and Co/Fe/Ni on Mn, respectively, on the specific capacitance of SrMnO 3 nanofibers is studied. 20 mol% Ba loading shows the best performance as a supercapacitor electrode with a specific capacitance of 446.8 F g –1 at a discharge current density of 0.5 A g –1 . The nanofibers retained 87% its initial capacitance after 5000 successive cycles. The device fabricated using the nanofibers show an energy density of 37.3 W h kg –1 at a power density of 400 W kg –1 , and it is retained as 15.7 W h kg –1 even at a high-power density of 8006 W kg –1 , indicating the potential of this electrode material for high-rate charge/discharge operations in supercapacitors.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Stable, Microfabricated Thin Layer Chromatography Plates without Volume Distortion on Patterned, Carbon and Al2O3-Primed Carbon Nanotube Forests

In a recent report (Song, J.; et al., Advanced Functional Materials 2011, 21, 1132-1139) some of us described the fabrication of thin layer chromatography (TLC) plates from patterned carbon nanotube (CNT) forests, which were directly infiltrated/coated with silicon by low pressure chemical vapor deposition (LPCVD) of silicon using SiH4. Following infiltration, the nanotubes were removed from the assemblies and the silicon simultaneously converted to SiO2 in a high temperature oxidation step. However, while straightforward, this process had some shortcomings, not the least of which was some distortion of the lithographically patterned features during the volume expansion that accompanied oxidation. Herein we overcome theis issue and also take substantial steps forward in the microfabrication of TLC plates by showing: (i) A new method for creating an adhesion promotion layer on CNT forests by depositing a few nanometers of carbon followed by atomic layer deposition (ALD) of Al2O3. This method for appears to be new, and X-ray photoelectron spectroscopy confirms the expected presence of oxygen after carbon deposition. ALD of Al2O3 alone and in combination with the carbon on patterned CNT forests was also explored as an adhesion promotion layer for CNT forest infiltration. (ii) Rapid, conformal deposition of an inorganic material that does not require subsequent oxidation: fast pseudo-ALD growth of SiO2 via alumina catalyzed deposition of tris(tert-butoxy)silanol onto the carbon/Al2O3-primed CNT forests. (iii) Faithful reproduction of the features in the masks used to microfabricate the TLC plates (M-TLC) this advance springs from the previous two points. (iv) A bonded (amino) phase on a CNT-templated microfabricated TLC plate. (v) Fast, highly efficient (125,000 - 225,000 N/m) separations of fluorescent dyes on M-TLC plates. (vi) Extensive characterization of our new materials by TEM, SEM, EDAX, DRIFT, and XPS. (vii) A substantially lower process temperature for the removal of the CNT scaffold as a result of the (already oxidized) materials used in this study.

36 MATERIALS SCIENCE↗
DOE OSTI2015

How do energetic ions damage metallic surfaces?

Surface modification under bombardment by energetic ions observed under different conditions in structural and functional materials and can be either unavoidable effect of the conditions or targeted modification to enhance materials properties. Understanding basic mechanisms is necessary for predicting properties changes. The mechanisms activated during ion irradiation are of atomic scale and atomic scale modeling is the most suitable tool to study these processes. In this paper we present results of an extensive simulation program aimed at developing an understanding of primary surface damage in iron by energetic particles. We simulated 25 keV self-ion bombardment of Fe thin films with (100) and (110) surfaces at room temperature. A large number of simulations, ~400, were carried out allow a statistically significant treatment of the results. The particular mechanism of surface damage depends on how the destructive supersonic shock wave generated by the displacement cascade interacts with the free surface. Three basic scenarios were observed, with the limiting cases being damage created far below the surface with little or no impact on the surface itself, and extensive direct surface damage on the timescale of a few picoseconds. In some instances, formation of large <100> vacancy loops beneath the free surface was observed, which may explain some earlier experimental observations.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Dual-ion ECRAM as a stable and accurate analog synapse

Electrochemical random-access memory (ECRAM) works by tuning the bulk electronic conductance of functional materials via reversible, electrochemical insertion of ions, resulting in stable analog resistive switching, attractive for analog in-memory and neuromorphic computing. However, achieving fast programming for training and long retention for inference has been elusive. Protonic ECRAM demonstrates fast programming but insufficient retention, while oxygen-based ECRAM with excellent retention requires elevated programming temperatures. Cu-based ECRAM offers a compromise, with an activation energy (E A ) of ≈0.76 eV between protons (E A ≈ 0.4 eV) and oxygen (E A > 1 eV), enabling extensive retention and room temperature programming. Combining Cu 2+ ions with protons to form a dual-ion ECRAM, we demonstrate two distinct switching behaviors: fast switching at ≤5 V, (E A ≈ 0.45 eV) via protons, and nonvolatile, room temperature switching at ≥8 V, with E A ≈ 0.76 eV via Cu 2+ ions. In conclusion, the Cu-based state exhibits a wide conductance range, with excellent retention, low noise, and linear current-voltage behavior, achieving digital-equivalent ImageNet inference accuracy.

analog in-memory computing↗
DOE OSTI2019

Ballistic-diffusive phonon transport in cellulose nanocrystals by ReaxFF molecular dynamics simulations

Cellulose nanocrystals (CNCs), a ubiquitous nano-sized natural biopolymer, have drawn considerable attention in recent years due to their excellent mechanical and chemical properties. However, thermal properties of CNCs, which are critical for their potential applications as structural or functional materials, are less investigated. In this work, their thermal properties were systematically studied by molecular dynamics (MD) simulations in terms of the effects of polymorphs, size, temperature, and strain. It was found that the thermal conductivities depend on the polymorphs of CNCs, but the thermal conductance of unit chain of each polymorph is similar. Moreover, the strong dependence of the thermal conductivities of CNCs on their length and cross-sectional area indicates the existence of remarkable ballistic-diffusive phonon transport. Single chain CNCs can achieve a thermal conductivity of ~6 W/(m∙K), implying their potential as high thermal conductive polymer. The mechanical strain can enhance the alignment of cellulose skeleton, which reduces phonon scattering and thus increases thermal conductivity. Possible underlying mechanism of the varying thermal conductivity was further discussed and attributed to the shift of phonon frequencies and varied degree of orientation. This study reveals the sophisticated ballistic-diffusive phonon transport in CNCs, and pave path to future design of CNC-based materials with desirable thermal properties.

42 ENGINEERING↗