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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Elimination of NO Pollutant in Semi-enclosed Spaces over Sodium-promoted Cobalt Oxyhydroxide (CoOOH) by Oxidation and Adsorption Mechanism

Low concentrations of NOx accumulated in air in semi-enclosed spaces is a severe health hazard, but its efficient removal at low cost is a grand challenge. A simple method in preparing CoOOH for low-concentration NO removal at room temperature is described here. The samples are synthesized by oxidizing Co(OH)2 to CoOOH with different oxidants (Na2S2O8, O2 and H2O2). Among them, CoOOH prepared by Na2S2O8 (Co-NS) shows remarkable performance for NO abatement, while the samples synthesized by and H2O2 (Co-HO) and O2 (Co-OG) have no apparent NO removal capacity. It is found that the Co-NS material contains a higher concentration of residual Na, which contributes to the decreased crystallinity and increased concentrations of surface active species (Co2+, active oxygen) for NO storage. Following NO storage, the material can be readily regenerated by water washing. The authors from East China University of Science and Technology acknowledge support from National Basic Research Program of China (2013CB933200), National Natural Science Foundation of China (21577035, 21577034), Commission of Science and Technology of Shanghai Municipality (15DZ1205305) and 111 Project (B08021). Aiyong Wang acknowledges the China Scholarship Council for the Joint-Training Scholarship Program with the Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the US DOE under contract DE-AC05-76RL01830. FG is supported by the U.S. DOE/Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office.

NOx abatement, NOx adsorber, ambient temperature, ↗
DOE OSTI2020

Ultra-high aspect ratio pores milled in diamond via laser, ion and electron beam mediated processes

Microfabrication techniques are critical for the rapid prototyping and development of applications for cutting edge materials. Recently diamond has gained considerable interest for quantum photonic, biosensing, inertial confinement fusion and magnetometer applications. In this article, ultra-high aspect ratio milling of diamond micropores by photon, ion and electron based methods is reported. A multiphoton absorption laser ablation approach is revealed to rapidly produce sub-10 μm diameter micropores in diamond with an aspect ratio of 14:1 and a tapered profile at the surface interface. Chemically active, oxygen focused ion beam milling produces high-aspect ratio pores in diamond with an aspect ratio of 65:1 and minimal tapering over the length of the pore, overcoming the physical interaction volume limitations imposed in conventional gallium based focused ion beam milling and laser ablation methods. Oxygen-mediated electron beam induced etching is revealed to negate the limitations imposed by physical sputtering mechanisms utilized in focused ion beam milling via the direct initiation of chemical reactions at the receding surface, producing aspect ratios on the order of 200:1. Numerical simulations reveal the physical basis for the superior aspect-ratio pore milling of the oxygen focused ion beam milling and electron beam induced etching methods. Our results demonstrate direct-write methods for the fabrication of ultra-high aspect micropores in diamond and provide insight into the underlying mechanisms of these physical processes. The three methods demonstrated here can be interchanged for applications based on the desired characteristic aspect ratio and process throughput.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Kinetically versus thermodynamically controlled factors governing elementary pathways of GaP(111) surface oxidation

GaP and related III-V semiconductors have attracted interest as high-efficiency photoelectrochemical electrodes for solar water splitting. However, their efficacy is linked to the presence, identity, and integrity of native surface oxides, which are structurally and chemically complex and evolve during operation. Using ambient pressure X-ray photoelectron spectroscopy (APXPS) coupled with ab initio simulations, we track key chemical motifs expressed during evolution of GaP(111) surface oxides, their associated reaction kinetics, and their correlations with electronic properties. We identify two distinct thermal regimes corresponding to kinetically and thermodynamically controlled oxidation. Below 600 K, exposure to O2 generates kinetically facile Ga-O-Ga configurations, whereas higher temperatures cause activated oxygen to insert into Ga–P bonds as part of a thermodynamically driven transformation into a complex, heterogeneous 3D network of surface POx (1≤x ≤ 4) groups and Ga2O3 species, the latter of which eventually dominates upon depletion of surface phosphorus. Here our study highlights the critical competition between kinetic and thermodynamic factors during GaP oxidation, yielding insights for fabricating stable III-P-based photoelectrodes with precisely engineered surface properties.

08 HYDROGEN↗
DOE OSTI2022

Intra-crystalline mesoporous zeolite encapsulation-derived thermally robust metal nanocatalyst in deep oxidation of light alkanes

Zeolite-confined metal nanoparticles (NPs) have attracted much attention owing to their superior sintering resistance and broad applications for thermal and environmental catalytic reactions. However, the pore size of the conventional zeolites is usually below 2 nm, and reactants are easily blocked to access the active sites. Herein, a facile in situ mesoporogen-free strategy is developed to design and synthesize palladium (Pd) NPs enveloped in a single-crystalline zeolite (silicalite-1, S-1) with intra-mesopores (termed Pd@IM-S-1). Pd@IM-S-1 exhibited remarkable light alkanes deep oxidation performances, and it should be attributed to the confinement and guarding effect of the zeolite shell and the improvement in mass-transfer efficiency and active metal sites accessibility. The Pd–PdO interfaces as a new active site can provide active oxygen species to the first C–H cleavage of light alkanes. This work exemplifies a promising strategy to design other high-performance intra-crystalline mesoporous zeolite-confined metal/metal oxide catalysts for high-temperature industrial thermal catalysis.

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

Reactive boride infusion stabilizes Ni-rich cathodes for lithium-ion batteries

Engineered polycrystalline electrodes are critical to the cycling stability and safety of lithium-ion batteries, yet it is challenging to construct high-quality coatings at both the primary- and secondary-particle levels. Here, we present a room-temperature synthesis route to achieve full surface coverage of secondary particles and facile infusion into grain boundaries, thus offering a complete “coating-plus-infusion” strategy. Cobalt boride metallic glass is successfully applied to Ni-rich layered cathode LiNi 0.8 Co 0.1 Mn 0.1 O 2 . Here, it dramatically improves the rate capability and cycling stability, including under high-discharge-rate and elevated-temperature conditions and in pouch full cells. The superior performance originates from simultaneous suppression of microstructural degradation of intergranular cracking and side reactions with electrolyte. Atomistic simulations identified the critical role of strong selective interfacial bonding, which offers not only a large chemical driving force to ensure uniform reactive wetting and facile infusion but also lowered the surface/interface oxygen activity, contributing to the exceptional mechanical and electrochemical stabilities of the infused electrode.

25 ENERGY STORAGE↗
DOE OSTI2025

Synergistic effects of Pd single atoms and nanoclusters boosting SnO 2 gas sensing performance

Tin(IV) oxide-supported Pd is a promising heterogenous catalyst for CO oxidation relevant for environmental cleanup reactions. In this study, an atomically dispersed Pd catalyst on SnO 2 (ADC Pd/SnO 2 ) hybrid material is successfully synthesized via a straightforward wet chemistry method and is found to exhibit superior performance toward CO sensing. Ex situ EXAFS analysis confirms the formation of single Pd atoms and small Pd nanoclusters stabilized on the SnO 2 (110) surface. Further, the material exhibits high efficiency in generating adsorbed O 2 - as well as high activity in catalyzing CO oxidation at low temperatures, resulting in exceptional sensitivity and selectivity toward CO in comparison to pure SnO 2 and Pd nanoparticles loaded on SnO 2 respectively. In situ FTIR measurements unravel CO adsorption kinetics on ADC Pd/SnO 2 under reaction conditions, and a possible sensing mechanism is put forth in which CO is transformed into CO 2 by reaction with active oxygen species; and concurrently, carbon-related species (bicarbonates and carbonates) are formed and decomposed into CO 2 .

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

Thermophysical modeling of raw glaze liquidus temperature and viscosity

Raw glazes, which do not contain pre-melted glass frits, are widely used due to their low cost. The natural variability of the mineral compositions used in raw glazes affects their viscosity during firing. Molten glaze viscosity plays an important role in determining the final surface quality; therefore, it is important to determine how raw glaze composition and firing conditions affect viscosity. Thermophysical modeling provides a way to evaluate the liquidus temperature and viscosity of molten glazes as a function of composition and oxygen activity. Equilibrium phase volume fraction and composition of 242 raw glaze recipes were evaluated under oxidizing and reducing conditions. Undissolved or precipitation of solid phases explain the secondary flux transition from anti-fluxing to fluxing near the liquidus temperature. The liquidus temperature and viscosity of iron glazes decrease as a function of increasing iron content under a reducing atmosphere. The empirical probability distribution of molten glaze viscosity follows a lognormal distribution, with lead glazes having significantly lower viscosity compared with glazes without lead. Here, the peak firing temperature viscosity of lead-free glazes is near the working point of glass. Multiple linear regression analysis shows that the peak firing temperature viscosity and liquidus temperature significantly predict the viscosity factor.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Critical Barriers to Successful Implementation of Earth-Abundant, Mn-Rich Cathodes for Vehicle Applications and Beyond: A Detailed Study of Low SOC Impedance

We report that earth-abundant, sustainable cathode chemistries based on Mn are increasingly attractive for enabling a broader portfolio of cathode oxides. The well-known class of lithium- and manganese-rich cathodes still represents very viable options. However, despite the important work on understanding the mechanisms of voltage fade, hysteresis, and oxygen activity, relatively little attention has been given to understanding the impedance characteristics of these electrodes. In particular, an anomalous rise in area specific impedance at lower states of charge, as well as overall impedance rise and surface damage due to electrolyte interactions, represent critical barriers to implementation. This work presents a comprehensive study of impedance behavior in cobalt-free, lithium- and manganese-rich electrodes. The use of a robust surface treatment allows for long-term behavior to be probed in the absence of surface damage, capacity loss, and impedance rise due to electrolyte interactions. The anomalous rise in impedance could not be correlated to surface changes, or surface phase formation, but could be directly correlated with the bulk processes of voltage fade and voltage hysteresis. The activated material can be explained as a percolating network of higher-voltage, layered-type sites having facile Li diffusion. Interspersed throughout this network are lower-voltage, disordered sites that represent a significant barrier.

25 ENERGY STORAGE↗
NASA NTRS1988

Sample selection and preservation techniques for the Mars sample return mission

It is proposed that a miniaturized electron spin resonance (ESR) spectrometer be developed as an effective, nondestructivew sample selection and characterization instrument for the Mars Rover Sample Return mission. The ESR instrument can meet rover science payload requirements and yet has the capability and versatility to perform the following in situ Martian sample analyses: (1) detection of active oxygen species, and characterization of Martian surface chemistry and photocatalytic oxidation processes; (2) determination of paramagnetic Fe(3+) in clay silicate minerals, Mn(2+) in carbonates, and ferromagnetic centers of magnetite, maghemite and hematite; (3) search for organic compounds in the form of free radicals in subsoil, and detection of Martian fossil organic matter likely to be associated with carbonate and other sedimentary deposits. The proposed instrument is further detailed.

Tsay, Fun-Dow↗
NASA NTRS2002

Using Isothermal Microcalorimetry to Determine Compatibility of Structural Materials with High-Test Hydrogen Peroxide (HTP) Propellant

High-Test Hydrogen Peroxide (HTP) propellant (equal to or greater than 70%) offers many advantages in space launch applications. However, materials used in construction of propulsion systems must be shown to be compatible with HTP. Isothermal Microcalorimetry (IMC) was used to determine the compatibility of several metallic and non-metallic materials with 90% HTP. The results of these experiments agreed with those from immersion bath tests when the values were converted to % Active Oxygen Loss per week (%AOL/wk).

Gostowski, Rudy↗
NASA NTRS2003

Using Isothermal Microcalorimetry to Determine Compatibility of Structural Materials with High Test Hydrogen Peroxide (HTP) Propellant

High-Test Hydrogen Peroxide (HTP) propellant (greater than or equal to 70%) offers many advantages in space launch applications; however, materials used in construction of propulsion systems must be shown to be compatible with HTP. Isothermal Microcalorimetry (IMC) was used to determine the compatibility of several metallic and non-metallic materials with 90% HTP. The results of these experiments agreed with those from immersion bath tests when the values were converted to %Active Oxygen Loss per week (%AOL/wk).

Gostowski, Rudy↗
DOE OSTI2024

A highly oxygen reduction reaction active and CO 2 durable high-entropy cathode for solid oxide fuel cells

One big obstacle for the oxygen reduction reaction (ORR) electrode in solid oxide fuel cells (SOFCs) is the poor reaction activity and fast degradations caused by CO 2 poisoning. Here, in this study, we report our design of an active A-site Ca-rich high-entropy Pr 0.1875 Ba 0.1875 Sr 0.1875 La 0.1875 Ca 0.25 CoO 3-δ (PBSLC 25 C) electrode, guided by the O p-band theory. Here, when applied as a cathode in solid oxide fuel cells (SOFCs), it demonstrates high ORR activity and excellent CO 2 tolerance under realistic operating conditions. Ni-YSZ-based anode-supported cells with PBSLC 25 C cathodes demonstrate excellent peak power densities of 1.14 W cm -2 , 1.04 W cm -2 , and 0.77 W cm -2 in the air with 1%, 5%, and 10% CO 2 , respectively, at 750 °C. The engineered high-entropy PBSLC 25 C effectively diminishes the CO 2 poisoning effect and maintains active surfaces for fast oxygen exchange, as confirmed by the cell durability test in air containing CO 2 (5 and 10 vol%), Raman spectroscopy, and density functional theory calculations.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2021

Verification of Maximal Oxygen Uptake in Active Military Personnel During Treadmill Running

Figueiredo, PS, Looney, DP, Pryor, JL, Doughty, EM, McClung, HL, Vangala, SV, Santee, WR, Beidleman, BA, and Potter, AW. Verification of maximal oxygen uptake in active military personnel during treadmill running. J Strength Cond Res 36(4): 1053–1058, 2022—It is unclear whether verification tests are required to confirm “true” maximal oxygen uptake ($\dot{V}_{o2}$max) in modern warfighter populations. Our study investigated the prevalence of $\dot{V}_{o2}$max attainment in U.S. Army soldiers performing a traditional incremental running test. In addition, we examined the utility of supramaximal verification testing as well as repeated trials for familiarization for accurate $\dot{V}_{o2}$max assessment. Sixteen U.S. Army soldiers (1 woman, 15men; age, 21±2 years; height, 1.73±0.06m; body mass, 71.6±10.1 kg) completed 2 laboratory visits, each with an incremental running test (modified Astrand protocol) and a verification test (110% maximal incremental test speed) on a motorized treadmill. We evaluated $\dot{V}_{o2}$max attainment during incremental testing by testing for the definitive $\dot{V}_{o2}$ plateau using a linear least-squares regression approach. Peak oxygen uptake ($\dot{V}_{o2}$peak) was considered statistically equivalent between tests if the 90% confidence interval around the mean difference was within 62.1 ml·kg -1 ·min -1 . Oxygen uptake plateaus were identified in 14 of 16 volunteers for visit 1 (87.5%) and all 16 volunteers for visit 2 (100%). Peak oxygen uptake was not statistically equivalent, apparent from the mean difference in $\dot{V}_{o2}$peak measures between the incremental test and verification test on visit 1 (2.3 ml·kg -1 ·min -1 , [1.3–3.2]) or visit 2 (1.1 ml·kg -1 ·min -1 [0.2–2.1]). Interestingly, $\dot{V}_{o2}$peak was equivalent, apparent from the mean difference in $\dot{V}_{o2}$peak measures between visits for the incremental tests (0.0ml·kg -1 ·min -1 [-0.8to 0.9]) but not the verification tests (-1.2 ml·kg -1 ·min -1 [-2.2 to -0.2]). Modern U.S. Army soldiers can attain $\dot{V}_{o2}$max by performing a modified Astrand treadmill running test. Additional familiarization and verification tests for confirming $\dot{V}_{o2}$max in healthy active military personnel may be unnecessary.

60 APPLIED LIFE SCIENCES↗
NASA NTRS2002

Labor Contractions Enhance Oxygenation and Behavioral Activity of Newborn Rat Pups

Labor contractions help instigate behavioral responses at birth (viz., breathing and suckling) that are vital for the newborn's adaptation to the extrauterine world (Ronca et al., 1996). In the present study, we analyzed the role of labor contractions in postpartum oxygenation and behavioral activity of newborn rat pups. Newborns were observed following either vaginal (V) or cesarean delivery. For cesarean delivery, day 21 pregnant dams' were administered a spinal transaction to eliminate lower body sensation, a laparotomy was performed and the uterus was maintained in a heated (37.5 C) bath. Four rat fetuses in one of the dams' paired uterine horn were compressed (C) to Simulate labor contractions (20 sec/min for 10 min) while four fetuses in the opposite horn were not compressed (NC). Fetuses were surgically removed from the uterus, stroked with a soft brush to mimic postnatal licking by the dam, the umbilical cord occluded. Pups were exposed to room temperature (22 C) for one hr, then nest temperature (33 C) for one hr. PO2, CO2, and O2, saturation were determined at 0, 30, 60, or 120 min post delivery using a blood gas analyzer. V and C delivered neonates showed comparable rates of PO2, CO2 and O2 saturation whereas NC neonates showed depressed levels at all time points (p<0.05). Respiratory rates of V, C and NC neonates increased significantly (p<0.05) over the first two postpartum hrs and did not differ across groups. Postpartum behavioral activity was significantly greater in V and C conditions and positively correlated with postnatal oxygenation. These findings provide further evidence for importance of labor contractions in early postpartum adaptation.

Mills, N. A.↗
DOE OSTI2023

Inhibition of Extracellular Enzyme Activity by Reactive Oxygen Species upon Oxygenation of Reduced Iron-Bearing Minerals

The dual roles of minerals in inhibiting and prolonging extracellular enzyme activity in soils and sediments are governed by enzyme adsorption to mineral surface. Oxigenation of mineral-bound Fe(II) generates reactive oxygen species (ROS), yet it is unknown whether and how this process alters the activity and functional lifespan of extracellular enzymes. Here, the effect of mineral-bound Fe(II) oxidation on the hydrolytic activity of a cellulose-degrading enzyme ß-glucosidase (BG) was studied using two pre-reduced Fe-bearing clay minerals (nontronite and montmorillonite) and one pre-reduced iron oxide (magnetite) at pH 5 and 7. Under anoxic condition, BG adsorption to mineral surface decreased its activity but prolonged its lifespan. Under oxic condition, ROS was produced, with the amount of •OH, the most abundant ROS, being positively correlated with the extent of structural Fe(II) oxidation in reduced minerals. •OH decreased BG activity and shortened its lifespan via conformational change and structural decomposition of BG. These results suggest that under oxic condition the ROS-induced inhibitory role of Fe(II)-bearing minerals outweighed their adsorption-induced protective role in controlling enzyme activity. These results disclose a previously unknown mechanism of extracellular enzyme inactivation, which have pivotal implications for predicting the active enzyme pool in redox-oscillating environments.

58 GEOSCIENCES↗
DOE OSTI2022

Atomically dispersed iron sites with a nitrogen–carbon coating as highly active and durable oxygen reduction catalysts for fuel cells

Nitrogen-coordinated single atom iron sites (FeN 4 ) embedded in carbon (Fe–N–C) are the most active platinum group metal-free oxygen reduction catalysts for proton-exchange membrane fuel cells. Still, current Fe–N–C catalysts lack sufficient long-term durability and are not yet viable for practical applications. Here we report a highly durable and active Fe–N–C catalyst synthesized using heat treatment with ammonia chloride followed by high-temperature deposition of a thin layer of nitrogen-doped carbon on the catalyst surface. We propose that catalyst stability is improved by converting defect-rich pyrrolic N-coordinated FeN 4 sites into highly stable pyridinic N-coordinated FeN 4 sites. The stability enhancement is demonstrated in membrane electrode assemblies using accelerated stress testing and a long-term steady-state test (>300 h at 0.67 V), approaching a typical Pt/C cathode (0.1 mg Pt cm -2 ). The encouraging stability improvement represents a critical step in developing viable Fe–N–C catalysts to overcome the cost barriers of hydrogen fuel cells for numerous applications.

08 HYDROGEN↗
DOE OSTI2020

Surface oxygenation of multicomponent nanoparticles toward active and stable oxidation catalysts

Abstract The need for active and stable oxidation catalysts is driven by the demands in production of valuable chemicals, remediation of hydrocarbon pollutants and energy sustainability. Traditional approaches focus on oxygen-activating oxides as support which provides the oxygen activation at the catalyst-support peripheral interface. Here we report a new approach to oxidation catalysts for total oxidation of hydrocarbons (e.g., propane) by surface oxygenation of platinum (Pt)-alloyed multicomponent nanoparticles (e.g., platinum-nickel cobalt (Pt–NiCo)). The in-situ/operando time-resolved studies, including high-energy synchrotron X-ray diffraction and diffuse reflectance infrared Fourier transform spectroscopy, demonstrate the formation of oxygenated Pt–NiOCoO surface layer and disordered ternary alloy core. The results reveal largely-irregular oscillatory kinetics associated with the dynamic lattice expansion/shrinking, ordering/disordering, and formation of surface-oxygenated sites and intermediates. The catalytic synergy is responsible for reduction of the oxidation temperature by ~100 °C and the high stability under 800 °C hydrothermal aging in comparison with Pt, and may represent a paradigm shift in the design of self-supported catalysts.

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

Atomic-scale identification of active sites of oxygen reduction nanocatalysts

Heterogeneous nanocatalysts play a crucial role in both the chemical and energy industries. Despite substantial advancements in theoretical, computational and experimental studies, identifying their active sites remains a major challenge. Here we utilize atomic electron tomography to determine the three-dimensional atomic structure of PtNi and Mo-doped PtNi nanocatalysts for the electrochemical oxygen reduction reaction. We then employ the experimental atomic structures as input to first-principles-trained machine learning to identify the active sites of the nanocatalysts. Through the analysis of the structure–activity relationships, we formulate an equation termed the local environment descriptor, which balances the strain and ligand effects to provide physical and chemical insights into active sites in the oxygen reduction reaction. The ability to determine the three-dimensional atomic structure and chemical composition of realistic nanoparticles, combined with machine learning, could transform our fundamental understanding of the active sites of catalysts and guide the rational design of optimal nanocatalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗