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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 1,477 records · Page 82
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Zero-strain high entropy spinel oxide (FeNiCuCrMn) 3 O 4 @rGO as high-performance anode for sodium ion battery

High entropy spinel oxides (HEOs), as a new type of anode material with at least five transition metal elements and high theoretical specific capacity, have enormous promise in sodium ion batteries (SIBs). However, the influence of different transition metal elements on the structure and electrochemical performances of HEOs is not clear. Here, in this study, the addition of Mn to HEO can increase the surface oxygen vacancy (O v ) concentration, shorten the band gap, and enhance the electrochemical performance of (FeNiCuCrMn) 3 O 4 @rGO. XPS results show (FeNiCuCrMn)3O4@rGO has the highest surface O v concentration. Ab initio calculations demonstrate that the indirect band gap of (FeNiCuCrMn)3O4@rGO is 0.068 eV. In situ X-ray diffraction and synchrotron X-ray absorption spectroscopy reveal that (FeNiCuCrMn) 3 O 4 @rGO exhibits a zero-strain characteristic with an inconsequential unit cell volume change of 0.2 %. Specifically, (FeNiCuCrMn) 3 O 4 @rGO as anode materials for SIBs show good cyclic stability (with a capacity retention of 84 % at 500 mA g −1 after 3000 cycles). Overall, this work provides a new direction for optimizing transition metal elements in HEOs.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Carbonation and CO{sub 2} uptake of concrete

This study developed a reliable procedure to assess the carbon dioxide (CO{sub 2}) uptake of concrete by carbonation during the service life of a structure and by the recycling of concrete after demolition. To generalize the amount of absorbable CO{sub 2} per unit volume of concrete, the molar concentration of carbonatable constituents in hardened cement paste was simplified as a function of the unit content of cement, and the degree of hydration of the cement paste was formulated as a function of the water-to-cement ratio. The contribution of the relative humidity, type of finishing material for the concrete surface, and the substitution level of supplementary cementitious materials to the CO{sub 2} diffusion coefficient in concrete was reflected using various correction factors. The following parameters varying with the recycling scenario were also considered: the carbonatable surface area of concrete crusher-runs and underground phenomena of the decreased CO{sub 2} diffusion coefficient and increased CO{sub 2} concentration. Based on the developed procedure, a case study was conducted for an apartment building with a principal wall system and an office building with a Rahmen system, with the aim of examining the CO{sub 2} uptake of each structural element under different exposure environments during the service life and recycling of the building. As input data necessary for the case study, data collected from actual surveys conducted in 2012 in South Korea were used, which included data on the surrounding environments, lifecycle inventory database, life expectancy of structures, and recycling activity scenario. Ultimately, the CO{sub 2} uptake of concrete during a 100-year lifecycle (life expectancy of 40 years and recycling span of 60 years) was estimated to be 15.5%–17% of the CO{sub 2} emissions from concrete production, which roughly corresponds to 18%–21% of the CO{sub 2} emissions from the production of ordinary Portland cement. - Highlights: • CO{sub 2} uptake assessment approach owing to the concrete carbonation is developed. • An equation to directly determine the absorbable CO{sub 2} amount in concrete is proposed. • The carbonatable surface area of concrete crusher-runs for CO{sub 2} uptake is ascertained. • This study provides typical data for uptake and emission of CO{sub 2} in concrete building.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Fabrication of ultrafine manganese oxide-decorated carbon nanofibers for high-performance electrochemical capacitors

Ultrafine manganese oxide-decorated carbon nanofibers (MnOn-CNF) as a new type of electrode materials are facilely fabricated by direct conversion of Mn, Zn-trimesic acid (H3BTC) metal organic framework fibers (Mn-ZnBTC). The construction and evolution of Mn-ZnBTC precursors are investigated by SEM and in situ high-energy XRD. The manganese oxides are highly dispersed onto the porous carbon nanofibers formed simultaneously, verified by TEM, X-ray absorption fine structure (XAFS), Raman, ICP-AES and N2 adsorption techniques. As expected, the resulting MnOn-CNF composites are highly stable, and can be cycled up to 5000 times with a high capacitance retention ratio of 98% in electrochemical capacitor measurements. They show a high capacitance of up to 179 F g–1 per mass of the composite electrode, and a remarkable capacitance of up to 18290 F g–1 per active mass of the manganese(IV) oxide, significantly exceeding the theoretical specific capacitance of manganese(IV) oxide (1370 F g–1). The maximum energy density is up to 19.7 Wh kg–1 at the current density of 0.25 A g–1, even orders higher than those of reported electric double-layer capacitors and pseudocapacitors. The excellent capacitive performance can be ascribed to the joint effect of easy accessibility, high porosity, tight contact and superior conductivity integrated in final MnOn-CNF composites.

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

Environmental exposure to TiO 2 nanomaterials incorporated in building material

Nanomaterials are increasingly being used to improve the properties and functions of common building materials. A new type of self-cleaning cement incorporating TiO 2 nanomaterials (TiO 2 -NMs) with photocatalytic properties is now marketed. This promising cement might provide air pollution-reducing properties but its environmental impact must be validated. During cement use and aging, an altered surface layer is formed that exhibits increased porosity. The surface layer thickness alteration and porosity increase with the cement degradation rate. The hardened cement paste leaching behavior has been fully documented, but the fate of incorporated TiO 2 -NMs and their state during/after potential release is currently unknown. In this study, photocatalytic cement pastes with increasing initial porosity were leached at a lab-scale to produce a range of degradation rates concerning the altered layer porosity and thickness. No dissolved Ti was released during leaching, only particulate TiO 2 -NM release was detected. The extent of release from this batch test simulating accelerated worst-case scenario was limited and ranged from 18.7 ± 2.1 to 33.5 ± 5.1 mg of Ti/m 2 of cement after 168 h of leaching. TiO 2 -NMs released into neutral aquatic media (simulate pH of surface water) were not associated or coated by cement minerals. The TiO 2 -NM release mechanism is suspected to start from freeing of TiO 2 -NMs in the altered layer pore network due to partial cement paste dissolution followed by diffusion into the bulk pore solution to the surface. The extent of TiO 2 -NM release was not solely related to the cement degradation rate.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Palm oil deoxygenation with glycerol as a hydrogen donor for renewable fuel production using nickel-molybdenum catalysts: The effect of support

Palm oil, one of the most widely used vegetable oils, offers significant potential as a sustainable feedstock for biofuel production. This study explores the deoxygenation of palm oil using glycerol as a hydrogen donor, with nickel-molybdenum (NiMo) catalysts supported on commercial alumina (Al 2 O 3 ), and zeolite (HZSM-5) comparing with self-prepared zirconia (ZrO 2 ). The catalysts were synthesized via incipient wetness impregnation and evaluated for their performance in biofuel production. NiMo/Al 2 O 3 exhibited the lowest oxygen removal efficiency (68.5 %), while NiMo/HZSM-5 achieved a higher oxygen removal (74.3 %) but also demonstrated the highest coke formation. The type of support material influenced the resulting biofuel range, with NiMo/HZSM-5 and NiMo/ZrO 2 favoring jet fuel production, whereas NiMo/Al 2 O 3 was more suitable for diesel production. Notably, NiMo/ZrO 2 exhibited the highest performance in palm oil deoxygenation while minimizing coke formation. These findings highlight NiMo/ZrO 2 as a promising catalyst for efficient and stable biofuel production, with the support material significantly influencing product yield and fuel quality.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Targeting Nucleophosmin 1 Represents a Rational Strategy for Radiation Sensitization

Purpose: To test the hypothesis that small molecule targeting of nucleophosmin 1 (NPM1) represents a rational approach for radiosensitization. Methods and Materials: Wilde-type and NPM1-deficient mouse embryo fibroblasts (MEFs) were used to determine whether radiosensitization produced by the small molecule YTR107 was NPM1 dependent. The stress response to ionizing radiation was assessed by quantifying pNPM1, γH2AX, and Rad51 foci, neutral comet tail moment, and colony formation. NPM1 levels in a human-derived non-small-cell lung cancer (NSCLC) tissue microarray (TMA) were determined by immunohistochemistry. YTR107-mediated radiosensitization was assessed in NSCLC cell lines and xenografts. Results: Use of NPM1-null MEFs demonstrated that NPM1 is critical for DNA double- strand break (DSB) repair, that loss of NPM1 increases radiation sensitivity, and that YTR107-mediated radiosensitization is NPM1 dependent. YTR107 was shown to inhibit NPM1 oligomerization and impair formation of pNPM1 irradiation-induced foci that colocalized with γH2AX foci. Analysis of the TMA demonstrated that NPM1 is overexpressed in subsets of NSCLC. YTR107 inhibited DNA DSB repair and radiosensitized NSCLC lines and xenografts. Conclusions: These data demonstrate that YTR107-mediated targeting of NPM1 impairs DNA DSB repair, an event that increases radiation sensitivity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Concurrent Chemoradiation Therapy Followed by Consolidation Chemotherapy for Localized Extranodal Natural Killer/T-Cell Lymphoma, Nasal Type

Purpose: To evaluate the effectiveness of concurrent chemoradiation therapy (CCRT) with 40 Gy followed by consolidation chemotherapy for localized extranodal natural killer (NK)/T-cell lymphoma (ENKTL), nasal type. Methods and Materials: From August 2004 to August 2012, 62 patients with newly diagnosed stage IE to IIE ENKTL underwent CCRT followed by consolidation chemotherapy. The median RT dose was 40 Gy. Cisplatin, 30 mg/m{sup 2}, was administered weekly during the RT course. Responders to CCRT were encouraged to undergo consolidation chemotherapy. Three different consolidation chemotherapy regimens were used consecutively: VIPD (etoposide, ifosfamide, cisplatin, and dexamethasone); VIDL (etoposide, ifosfamide, and dexamethasone followed by intramuscular injection of L-asparaginase); and MIDLE (methotrexate, etoposide, ifosfamide, mesna, and L-asparaginase). Results: The median follow-up period was 49 months (range 8-112). After completion of CCRT, 56 patients (90.3%) had a complete response, 4 (6.4%) had a partial response, 1 (1.6%) had stable disease, and 1 patient (1.6%) had progressive disease (PD). Consolidation chemotherapy was recommended to 61 patients, after excluding the patient with PD, but was actually delivered to 58. Of these 58 patients, 56 (96.5%) had a complete response and 2 (3.5%) had PD. During the follow-up period, 17 patients (including 3 with PD) experienced progression. The median interval to progression was 11 months (range 1-61). Local failure developed in 6 patients, of whom, 2 had developed progression outside the RT field. For all patients, the 3-year overall survival, progression-free survival, and local control rates were 83.1%, 77.1%, and 92.4%, respectively. Grade ≥3 nonhematologic toxicity developed in only 3 patients (4.8%). Conclusions: Excellent clinical outcomes were achieved using CCRT with 40 Gy followed by consolidation chemotherapy. Additional investigation, however, is warranted to confirm our findings.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

Design of a bifunctional TEMPO-tertiary amine mesoporous silica catalyst for the three-step cascade synthesis of a chromene derivative

A key challenge is design of materials and processes whereby competing reagents or conditions do not harm the multi-step sequence, thus allowing for more efficient chemical synthesis with elimination of work-up and separation steps. In this work, a three-step reaction cascade is performed using a porous bifunctional dimethylpropylamine-TEMPO-MCM41 catalyst, converting the commodity chemicals benzyl alcohol, sodium hypochlorite, and malononitrile to a biologically active anti-cancer, and anti-malarial 2-amino-chromene derivative. The cascade first utilizes a TEMPO-catalyzed oxidation of benzyl alcohol to benzaldehyde with NaOCl as the terminal oxidant. This is followed by a two-step, dual base catalyzed Knoevenagel condensation with malononitrile followed by a Michael addition with lawsone. Optimal conditions converting benzyl alcohol to 2-amino-5,10-dioxo-4-phenyl-5,10-dihydro-4H-benzo[g]chromene-3-carbonitrile include the delayed addition of malononitrile and lawsone during the three-step reaction sequence, which results in a 2-amino-chromene yield of over 80%. The importance of stepwise reagent addition is rationalized due to the unfavorable adsorption of acidic lawsone on the surface-grafted base catalyst. Tertiary Brønsted base sites of dimethylpropylamine outperform the more Lewis basic primary propylamine functionalized catalyst. This work outlines a simple and effective method for generating mesoporous materials with two types of active sites via co-condensation and thiol-ene coupling procedures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Characterization of EJ-270 and Ce-doped LiCAF scintillators for the development of high-rate neutron reflectometer detectors

The Second Target Station of the Spallation Neutron Source at Oak Ridge National Laboratory is anticipated to provide a neutron source with ∼20 times increase in peak brightness than the First Target Station. The neutron reflectometers currently in operation at the First Target Station need to be upgraded due to the increased neutron flux. A prototype neutron detector module based upon a pixelated scintillator array readout by silicon photomultipliers is being developed to address the high-rate challenge faced with future neutron reflectometer instruments at the Second Target Station. Two types of scintillator materials were considered for this detector development, i.e., 6 Li-loaded EJ-270 plastic scintillator and Ce-doped LiCAF single crystal. This paper reports the scintillator characterization results, including light yield, pulse shape discrimination performance, capability to detect thermal neutrons in a high γ-ray field, and γ-ray sensitivity. The number of photons produced per neutron capture by EJ-270 and LiCAF:Ce was measured to be 2176 ± 91 and 2651 ± 108, respectively. EJ-270 demonstrated a good capability to discriminate between neutrons and γ-rays by employing the commonly used charge comparison method (figure-of-merit: 1.13 ± 0.01 for an energy cut of 292–426 keVee) and a reasonable performance when using the time-over-threshold techniques; however, no discrimination was observed from LiCAF:Ce regardless of the pulse shape discrimination approaches utilized, making pulse height discrimination necessary for LiCAF:Ce to differentiate between neutrons and γ-rays. Both EJ-270 and LiCAF:Ce exhibited an acceptable capacity to detect thermal neutrons at high exposure rates up to approximately 584 mR/h. Furthermore, the γ-ray sensitivities measured with a 60 Co source at an exposure rate of around 1145 mR/h were determined to be (6.11 ± 0.87) × 10 −6 and (7.64 ± 1.08) × 10 −7 for EJ-270 and LiCAF:Ce, respectively.

EJ-270↗
DOE OSTI2019

Machine Learning Optimization of p-Type Transparent Conducting Films

p-Type transparent conducting materials (p-TCMs) are important components of optoelectronic devices including solar cells, photodetectors, displays, and flexible sensors. Cu–Zn–S thin films prepared by chemical bath deposition (CBD) can have both high transparency in the visible range (>80%) as well as excellent hole conductivity (>1000 S cm –1 ). However, the interplay between the deposition parameters in the CBD process (metal and sulfur precursor concentrations, temperature, pH, complexing agents, etc.) creates a multidimensional parameter space such that optimization for a specific application is challenging and time-consuming. Here we show that strategic design of experiment combined with machine learning (ML) allows for the efficient optimization of p-TCM performance. The approach is guided by a figure of merit (FOM) calculated from the film conductivity and optical transmission in the desired spectral range. A specific example is shown using two steps of optimization using a selected subset of four experimental CBD factors. The ML model is based on support vector regression employing a radial basis function as the kernel function. 10-fold cross-validation was performed to mitigate overfitting. After the first round of optimization, predicted areas in the parameter space with maximal FOMs were selected for a second round of optimization. Films with optimal FOMs were incorporated into heterojunction solar cells and transparent photodiodes. Here, the optimization approach shown here will be generally applicable to any materials synthesis process with multiple parameters.

14 SOLAR ENERGY↗
DOE OSTI2025

Raman Fingerprints of Phase Transitions and Ferroic Couplings in van der Waals Multiferroic CuCrP 2 S 6

CuCrP 2 S 6 (CCPS), a type-II multiferroic material, exhibits unique phase transitions involving ferroelectric, antiferroelectric, and antiferromagnetic ordering. Here, in this study, we conduct a comprehensive investigation on the intricate phase transitions and their multiferroic couplings in CCPS across a wide temperature range from 4 to 345 K through Raman spectroscopic measurements down to 5 cm –1 . We first assign the observed Raman modes with the support of theoretical calculations and angle-resolved polarized Raman measurements. We further present clear signatures of phase transitions from the analyses of temperature-dependent Raman spectral parameters. Particularly, two low-frequency soft modes are observed at 36.1 cm –1 and 70.5 cm –1 below 145 K, indicating the antiferroelectric to quasi-antiferroelectric transition. Moreover, phonon mode hardening is observed when the temperature increases from 4 to 65 K, suggesting negative thermal expansion (NTE) and strong magnetoelastic coupling below 65 K. These findings advance the understanding of vdW multiferroic CCPS, paving the way for future design and engineering of multiferroicity in cutting-edge technologies, such as spintronics and quantum devices.

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

Giant Light-Emission Enhancement in Lead Halide Perovskites by Surface Oxygen Passivation

Surface condition plays an important role in the optical performance of semiconductor materials. As new types of semiconductors, the emerging metal-halide perovskites are promising for next-generation optoelectronic devices. We discover significantly improved light-emission efficiencies in lead halide perovskites due to surface oxygen passivation. The enhancement manifests close to 3 orders of magnitude as the perovskite dimensions decrease to the nanoscale, improving external quantum efficiencies from <0.02% to over 12%. Along with about a 4-fold increase in spontaneous carrier recombination lifetimes, we show that oxygen exposure enhances light emission by reducing the nonradiative recombination channel. Supported by X-ray surface characterization and theoretical modeling, we propose that excess lead atoms on the perovskite surface create deep-level trap states that can be passivated by oxygen adsorption.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Microporous Crystalline Membranes for Kr/Xe Separation: Comparison between AlPO-18, SAPO-34, and ZIF-8

Herein we demonstrate the separation ability of AlPO-18 membranes for Kr/Xe gas mixtures. AlPO-18 membranes separated Kr/Xe mixtures with average Kr/Xe separation selectivity of 6.4 and unprecedented high average Kr permeance of 1.6 × 10-7 mol/m2·s·Pa. Diffusivity difference between Kr and Xe was identified as the dominant separation mechanism. We compared the separation performance of AlPO-18 membranes versus two other types of microporous crystalline membranes, namely, SAPO-34 and ZIF-8. SAPO-34 membranes displayed the best overall separation performance, while AlPO-18 membranes displayed the highest Kr permeances. We identified the key factors affecting both the separation selectivity and permeance. For these three distinctive types of microporous materials, the presence of rigid micropores with size lying between Kr and Xe atomic sizes, lower Xe/Kr uptakes (adsorption selectivity), and lower concentration of nonselective pores led to the highest observed s Kr/Xe separation selectivities among these three microporous crystals. The Kr permeances for these three microporous crystalline membranes decreased exponentially as membrane thickness increased.

microporous crystals, membranes, gas separations, ↗
DOE OSTI2017

Doped Silicon Nanocrystal Plasmonics

Doped semiconductor nanocrystals represent an exciting new type of plasmonic material with optical resonances in the infrared. Unlike noble metal nanoparticles, the plasmon resonance can be tuned by altering the doping density. Recently, it has been shown that silicon nanocrystals can be doped using phosphorus and boron resulting in highly tunable infrared plasmon resonances. Due to the band structure of silicon, doping with phosphorus contributes light (transverse) and heavy (longitudinal) electrons, while boron contributes light and heavy holes and one would expect two distinct plasmon branches. In this work we develop a classical hybridization theory and a full quantum mechanical TDLDA approach for two-component carrier plasmas and show that the interaction between the two plasmon branches results in strongly hybridized plasmon modes. The antibonding mode where the two components move in phase is bright and depends sensitively on the doping densities. The low energy bonding mode with opposite charge alignment can only be observed in the quantum regime when strong Coulomb screening is present. The theoretical results are in good agreement with the experimental data.

42 ENGINEERING↗
DOE OSTI2016

First-Principles Prediction of Thermodynamically Stable Two-Dimensional Electrides

Two-dimensional (2D) electrides, emerging as a new type of layered material whose electrons are confined in interlayer spaces instead of at atomic proximities, are receiving interest for their high performance in various (opto)electronics and catalytic applications. Experimentally, however, 2D electrides have been only found in a couple of layered nitrides and carbides. We report new thermodynamically stable alkaline-earth based 2D electrides by using a first-principles global structure optimization method, phonon spectrum analysis, and molecular dynamics simulation. The method was applied to binary compounds consisting of alkaline-earth elements as cations and group VA, VIA, or VIIA nonmetal elements as anions. We also revealed that the stability of a layered 2D electride structure is closely related to the cation/anion size ratio; stable 2D electrides possess a sufficiently large cation/anion size ratio to minimize electrostatic energy among cations, anions, and anionic electrons. This work demonstrates a new avenue to the discovery of thermodynamically stable 2D electrides beyond experimental material databases and provides new insight into the principles of electride design.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Dimensionality of nanoscale TiO 2 determines the mechanism of photoinduced electron injection from a CdSe nanoparticle

Assumptions about electron transfer (ET) mechanisms guide design of catalytic, photovoltaic, and electronic systems. We demonstrate that the mechanism of ET from a CdSe quantum dot (QD) into nanoscale TiO 2 depends on TiO 2 dimensionality. The injection into a TiO 2 QD is adiabatic due to strong donor–acceptor coupling, arising from unsaturated chemical bonds on the QD surface, and low density of acceptor states. In contrast, the injection into a TiO 2 nanobelt (NB) is nonadiabatic, because the state density is high, the donor–acceptor coupling is weak, and multiple phonons accommodate changes in the electronic energy. The CdSe adsorbant breaks symmetry of delocalized TiO 2 NB states, relaxing coupling selection rules, and generating more ET channels. Both mechanisms can give efficient ultrafast injection. Furthermore, the dependence on system properties is very different for the two mechanisms, demonstrating that the fundamental principles leading to efficient charge separation depend strongly on the type of nanoscale material.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Electrochemically primed functional redox mediator generator from the decomposition of solid state electrolyte

Recent works into sulfide-type solid electrolyte materials have attracted much attention among the battery community. Specifically, the oxidative decomposition of phosphorus and sulfur based solid state electrolyte has been considered one of the main hurdles towards practical application. Here we demonstrate that this phenomenon can be leveraged when lithium thiophosphate is applied as an electrochemically "switched-on" functional redox mediator-generator for the activation of commercial bulk lithium sulfide at up to 70 wt.% lithium sulfide electrode content. X-ray adsorption near-edge spectroscopy coupled with electrochemical impedance spectroscopy and Raman indicate a catalytic effect of generated redox mediators on the first charge of lithium sulfide. In contrast to pre-solvated redox mediator species, this design decouples the lithium sulfide activation process from the constraints of low electrolyte content cell operation stemming from pre-solvated redox mediators. Reasonable performance is demonstrated at strict testing conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗