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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Chemical durability and surface alteration of lanthanide zirconates (A 2 Zr 2 O 7 : A = La-Yb)

Chemical durability of lanthanide zirconates (A 2 Zr 2 O 7 ) (A = La-Yb) under near-field environments is important for evaluating their application as potential nuclear waste forms. In this work, A 2 Zr 2 O 7 (A = La-Yb) are synthesized by spark plasma sintering with controlled microstructure and their chemical durability are evaluated in a nitric acid solution (pH = 1). Scanning transmission electron microscopy analysis reveals an amorphous passivation film either enriched with Zr or lanthanide. The complex chemistry of the passivation films can be correlated with a transition in corrosion mechanisms from a preferential release of lanthanide in La 2 Zr 2 O 7 to a preferential release of Zr in Er 2 Zr 2 O 7 and Yb 2 Zr 2 O 7 . These results suggest a dominant mechanism of incongruent dissolution and surface reorganization for the formation of passivation films. Strong correlations are identified between the leaching rates and cation ionic size, ionic potential, electronegativity differences between A-site cation and Zr, and bonding valence sum of oxygen, suggesting important impacts of structural and bonding characteristics in controlling chemical durability of lanthanide zirconates.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Atomic Layer Deposition (ALD) of Metal and Metal Oxide Films: A Surface Science Study (Final Report)

This is the final report for this project. The long-term objective of our project is to develop a general molecular-level picture of the surface chemistry associated with ALD processes. Our central hypothesis is that the chemistry of ALD precursors can differ significantly from that seen in solution. Awareness of such differences should provide general guidelines on what to watch for when synthesizing new ALD precursors and designing and optimizing new ALD processes, especially in terms of minimizing the incorporation of impurities in the growing films and of carrying out depositions under mild pressure and temperature conditions. The main objective of our research project has been to advance the fundamental knowledge of the surface chemistry of ALD precursors needed for the design and optimization of film deposition processes. A modern surface-science approach has been implemented to both elucidate the mechanism of the reactions of the precursors on the surface and characterize the composition and morphology of the growing films.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Atomic Layer Deposition (ALD) of Metal and Metal Oxide Films: A Surface Science Study (Final Report)

This is the final report for this project. The long-term objective of our project is to develop a general molecular-level picture of the surface chemistry associated with ALD processes. Our central hypothesis is that the chemistry of ALD precursors can differ significantly from that seen in solution. Awareness of such differences should provide general guidelines on what to watch for when synthesizing new ALD precursors and designing and optimizing new ALD processes, especially in terms of minimizing the incorporation of impurities in the growing films and of carrying out depositions under mild pressure and temperature conditions. The main objective of our research project has been to advance the fundamental knowledge of the surface chemistry of ALD precursors needed for the design and optimization of film deposition processes. A modern surface-science approach has been implemented to both elucidate the mechanism of the reactions of the precursors on the surface and characterize the composition and morphology of the growing films. In general, emphasis is being placed on: • Identifying the primary reactions that may lead to the deposition of clean films; •Identifying the secondary reactions that may help the ALD process, by, for instance, helping with the reduction (or oxidation) of the metal atom; • Identifying the secondary reactions that may lead to the deposition of undesirable impurities in the growing films; • Determining the kinetic parameters of the relevant surface reactions in order to define the optimum conditions for film deposition and to minimize impurity deposition. • Characterizing the nature of the resulting films, with focus on their stoichiometry and on the final oxidation states of the constituent elements; and • Using the information obtained to propose better precursors for given ALD processes.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Method of enhancing a DLC coated surface for enhanced multipaction resistance

A method for creating an enhanced multipaction resistant diamond-like coating (DLC) coating with lower Secondary Electron Emission (SEE) properties is performed on an initial surface by etching a DLC coating deposited on the surface after deposition and optionally creating interlayers to enhance adhesion mechanical properties between the DLC coating and the initial surface.

Nichol, Robert Michael↗
DOE OSTI2022

Scalable synthesis of supported catalysts using fluidized bed atomic layer deposition

Overcoating layers deposited on the surface of heterogeneous catalysts using atomic layer deposition (ALD) have been shown to increase catalyst activity, lifetime, and selectivity. In this study, we performed Al 2 O 3 ALD and Pd ALD in a commercial fluidized bed reactor on high surface area mesoporous powder supports to create overcoated catalysts with high precursor utilization. We investigated the reaction mechanism for both Al 2 O 3 ALD and Pd ALD using in situ mass spectrometry and developed a mathematical model to understand the precursor saturation behaviors. We characterized the catalyst samples using a variety of techniques to measure the surface area, porosity, composition, and surface chemistry of the overcoated catalysts. Finally, we used propane dehydrogenation as a probe reaction to evaluate the performance of the catalysts prepared by fluidized bed ALD.

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

Pathways for Sustainable Reaction Kinetics in Li-CO2 Batteries

Lithium-carbon dioxide (Li-CO2) batteries hold great promise for high-energy-density storage applications. However, advancing this technology as a sustainable alternative to Li-ion systems requires a deeper understanding of the underlying reaction mechanisms, which remain elusive. A key challenge stems from the added complexity introduced by the presence of oxygen (O2) in CO2 environment. In this study, we employed a stable Cu3(VBi)0.5Se4 mid-entropy catalyst and conducted a comprehensive investigation to uncover the underlying reaction mechanisms in Li-CO2 batteries under varying CO2/O2 ratios. Under pure CO2 conditions, the battery exhibits excellent rechargeability, sustaining up to 1200 cycles. However, at high current densities, the discharge potential drops significantly (below 2.0 V), primarily due to sluggish reaction kinetics caused by solid carbon formation. Interestingly, introducing O2 mitigates this limitation, leading to a 58% increase of the discharge potential (from 1.7 V to 2.7 V) at the high current density of 0.8 mA/cm2, signifying a substantial boost in energy output. Our results reveal that the reactions follow distinct pathways, shifting from surface- to solution-based mechanism, and may even exhibit coexistence of both mechanisms, depending on the CO2/O2 ratio. These findings offer new insights for designing high-performance and sustainable Li-gas batteries utilizing CO2 and O2 mixtures.

Ngo, Anh [University of illinois Chicago]↗
DOE OSTI2024

Mechanical morphotype switching as an adaptive response in mycobacteria

Invading microbes face a myriad of cidal mechanisms of phagocytes that inflict physical damage to microbial structures. How intracellular bacterial pathogens adapt to these stresses is not fully understood. Here, we report the discovery of a virulence mechanism by which changes to the mechanical stiffness of the mycobacterial cell surface confer refraction to killing during infection. Long-term time-lapse atomic force microscopy was used to reveal a process of “mechanical morphotype switching” in mycobacteria exposed to host intracellular stress. A “soft” mechanical morphotype switch enhances tolerance to intracellular macrophage stress, including cathelicidin. Both pharmacologic treatment, with bedaquiline, and a genetic mutant lacking uvrA modified the basal mechanical state of mycobacteria into a soft mechanical morphotype, enhancing survival in macrophages. Our study proposes microbial cell mechanical adaptation as a critical axis for surviving host-mediated stressors.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Basic Research of Intrinsic Tamper indication Markings and Patterns defined by Pulsed Laser Irradiation

With our previous research, it was found that surface asperities or roughness must be present to create periodic surface structures upon laser exposure. In particular, an initial rough surface morphology (such as that found with a machined surface) provides multiple sites for light scattering, which underlies the formation of periodic ripple morphologies. Light scattering from a random surface creates patterns of periodic structures (with complex orientations) that could be used as intrinsic markings for tagging materials and equipment. Despite these initial findings, the fundamental mechanisms that give rise to periodic surface structures and their characteristic shapes were not identified in prior research.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Creep behavior of an additively manufactured 9Cr steel in the as-built condition

Limited studies have evaluated the creep behavior of additively manufactured (AM) ferritic-martensitic (FM) steels. This work investigated the creep behavior of a 9Cr FM steel fabricated by powder blown directed energy deposition (DED) technique. Here, the creep testing at 550–650 °C and 150 MPa for the specimens along the deposition direction in the as-built condition, together with corresponding microstructural characterization, revealed a threshold temperature between 600 and 625 °C, below which the steel has creep resistance comparable with Grade 91 cross-welds and noticeably greater than 9Cr-1Mo steel. The threshold temperature distinguishes the creep behavior in two regimes differentiated in creep activation energy, creep deformation, and failure mechanism. Unlike the creep rupture surface ~45° from the loading direction when tested above the threshold temperature, the creep rupture for testing below the threshold temperature resembles type IV failure in the cross-welds of ferritic steels. The DED-induced layer structure in the as-built steel played a significant role on the change of creep behavior.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Alteration of pool boiling heat transfer on metallic surfaces by in situ oxidation

The critical heat flux during pool boiling has been investigated for a range of applications including electrical power generation and thermal management. Reported experimental CHF values during pool boiling of water on flat metallic surfaces, however, show a large discrepancy across studies. Here, we address this discrepancy in CHF values by accounting for oxidation of metallic surfaces during boiling. We studied the effect of in situ oxidation on flat Cu and Ni surfaces by changing the duration that samples were held in saturated water before conducting boiling experiments. The morphology and chemical composition of surfaces after the boiling experiments were analyzed by atomic force microscopy and X-ray photoelectron spectroscopy, respectively. Cu surfaces showed gradually increasing CHF values as the duration in saturated water increased, which could be attributed to the increase in roughness due to the formation of Cu 2 O nanostructures. Conversely, Ni surfaces showed relatively stable CHF and morphology as a nearly flat layer of NiO formed, with one exception: formation of a highly wetting hydroxide, Ni(OH) 2 , on a Ni coupon held in saturated water for 24 h resulted in a uniquely high CHF value, signifying the importance of surface chemistry in addition to morphology. Finally, the fundamental mechanisms resulting in the wide spread of CHF values on metallic surfaces elucidated in this work will lead to more accurate estimation of CHF as well as a deeper mechanistic understanding of CHF values on engineered surfaces.

42 ENGINEERING↗
DOE OSTI2021

Carbon decorated Li 3 V 2 (PO 4 ) 3 for high-rate lithium-ion batteries: Electrochemical performance and charge compensation mechanism

Fast charging and high-power delivering batteries are highly demanded in mobile electronics, electric vehicles and grid energy storage, but there are full of challenges. The star-material Li 3 V 2 (PO 4 ) 3 is demonstrated as a promising high-rate cathode material meeting the above requirements. Herein, we report the carbon decorated Li 3 V 2 (PO 4 ) 3 (LVP/C) cathode prepared via a facile method, which displays a remarkable high-rate capability and long-term cycling performance. Briefly, the prepared LVP/C delivers a high discharge capacity of 122 mAh g -1 (~93% of the theoretical capacity) at a high rate up to 20 C and a superior capacity retention of 87.1% after 1000 cycles. Importantly, by applying a combination of X-ray absorption spectroscopy and full-range mapping of resonant inelastic X-ray scattering, we clearly elucidate the structural and chemical evolutions of LVP upon various potentials and cycle numbers. Furthermore, we show unambiguous spectroscopic evidences that the evolution of the hybridization strength between V and O in LVP/C as a consequence of lithiation/delithiation is highly reversible both in the bulk and on the surface during the discharge-charge processes even over extended cycles, which should be responsible for the remarkable electrochemical performance of LVP/C. Our present study provides not only an effective synthesis strategy but also deeper insights into the surface and bulk electrochemical reaction mechanism of LVP, which should be beneficial for the further design of high-performance LVP electrode materials.

25 ENERGY STORAGE↗
DOE OSTI2026

Radiation Damage Mechanisms in Oxide-Based Solid Electrolytes

Ion implantation is a promising approach to mitigate dendrite formation in metal anode solid-state batteries by modifying the chemical and mechanical properties of oxide-based electrolyte surfaces such as Li 7 La 3 Zr 2 O 12 (LLZO). Yet, the detailed atomistic mechanisms and potentially adverse side effects of ion implantation remain poorly understood. In this study, we used molecular dynamics simulations to elucidate the evolution of radiation-induced damage in LLZO. The results reveal that radiation damage is primarily driven by recoils from heavy ions in the lattice, producing antisite defect clusters whose density decreases as recoil energy increases, a counterintuitive finding that highlights complex cascade fragmentation. Radiation-induced disruption to the crystal sublattice connectivity, especially in the La–O network critical for Li-ion transport, leads to degradation in ionic pathways at low energies, while higher energy cascades can form new conduction pathways via enhanced Zr–O network connectivity. These findings provide a mechanistic foundation for optimizing ion implantation strategies that balance disruption of the lattice for surface modification for dendrite resistance with preservation of essential ionic conductivity.

Defects↗
DOE OSTI2025

SAN-Based Block Polymers as a Platform for Manufacturing Strong Isoporous Membranes

Ultrafiltration (UF) membranes are ubiquitous in water purification and bioprocessing. However, co-designing their mechanical and transport properties remains challenging because of the broad pore size distributions at the surface and within the bulk that result from nonsolvent-induced phase separation (NIPS) – their typical manufacturing process. These distributions influence the hydrodynamic resistance to water flow and the stress concentrations around the pores. Developing advanced UF membranes requires innovative molecular designs that offer control over the surface and bulk pores, as well as the mechanical properties of the load-bearing, polymer. Here, we introduce a platform for designing UF membranes by leveraging solution self-assembly of block polymers and chain architectures with pendant polar groups. The block polymers consist of a poly(styrene-co-acrylonitrile) hydrophobic block, which is known for its strength, and a poly(4-vinyl pyridine) hydrophilic block, which drives solution self-assembly. We focus on a series of block polymers with constant molecular weight, M n ≈ 115 kDa, SAN fraction, 75 wt.%, and varying acrylonitrile content, 0 to 40 mol%, to demonstrate that: (i) RAFT dispersion copolymerization of acrylonitrile and styrene provides a facile route to synthesize strong block polymers, (ii) incorporation of acrylonitrile into the hydrophobic block enhances membrane strength by facilitating chain entanglements and dipole-dipole interactions, and (iii) acrylonitrile alters the balance between membrane permeance and rejection, even when the membranes feature similar surface and bulk pores. Overall, our results provide insights into the molecular design of UF membranes with enhanced mechanical and separation properties, contributing to the development of materials for water and energy technologies.

deformation↗
DOE OSTI2024

Potential–Dependent BDAC Adsorption on Zinc Enabling Selective Suppression of Zinc Corrosion for Energy Storage Applications

Utility-scale zinc (Zn) batteries are a promising solution to address the problem of intermittency of renewable energy sources; however, Zn-metal anodes in these batteries suffer from capacity loss due to spontaneous corrosion of the Zn especially when high-surface area anode configurations are employed. Additionally, Zn dendrites are known to form during battery charging limiting the cycle-life of these batteries. Electrolyte additives have been explored that prevent aforementioned issues, but these too come at a cost, i.e., surface-blocking additives polarize the electrode surface leading to loss in the voltaic and energy efficiencies of the battery. In this contribution, a novel electrolyte additive, benzyldimethylhexadecylammonium chloride (BDAC), is investigated for its ability to suppresses corrosion of Zn in an acidic (pH = 3) electrolyte. An attribute of BDAC distinct from previously studied additives is that it selectively suppresses electrochemical activity when the Zn electrode is at its corrosion potential; however, during high-rate Zn deposition (charging) or stripping (discharging), BDAC is essentially deactivated and thus it does not appreciably polarize the electrode surface, thus minimizing voltaic efficiency losses. This selective corrosion suppression behavior is explored using slow-scan voltammetry, which reveals hysteresis implying a potential- or current-dependent BDAC adsorption mechanism in which BDAC reaches higher surface coverages when the partial currents at the Zn surface are low (e.g., at or near the corrosion potential), but BDAC coverage is reduced considerably when the Zn deposition or stripping rates are increased. Numerical simulations of the BDAC diffusion-adsorption process corroborate this mechanism. Ramifications of our approach to the selective suppression of Zn dendrites are discussed.

25 ENERGY STORAGE↗
DOE OSTI2023

Review of the adsorbents/catalysts for the removal of sulfur compounds from natural gas

Here this paper aims to provide a compilation of studies on adsorptive removal of H2S and organic sulfur compounds from natural gas at relatively low temperatures and pressures. The manuscript compares sulfur uptakes among different materials, including zeolites, activated carbons, metallic organic frameworks (MOFs), and metal oxides, and the impact of modifications to these materials. Best sulfur uptakes were achieved by adding metallic or nitrogen species to the adsorbent surfaces. This contribution to the peer-reviewed literature could provide a better understanding of the improvements necessary to achieve greater sulfur capacities and the mechanisms of sulfur interactions with adsorbents' surfaces.

03 NATURAL GAS↗
DOE OSTI2022

Tailoring thermal insulation architectures from additive manufacturing

Abstract Tailoring thermal transport by structural parameters could result in mechanically fragile and brittle networks. An indispensable goal is to design hierarchical architecture materials that combine thermal and mechanical properties in a continuous and cohesive network. A promising strategy to create such a hierarchical network targets additive manufacturing of hybrid porous voxels at nanoscale. Here we describe the convergence of agile additive manufacturing of porous hybrid voxels to tailor hierarchically and mechanically tunable objects. In one strategy, the uniformly distributed porous silica voxels, which form the basis for the control of thermal transport, are non-covalently interfaced with polymeric networks, yielding hierarchic super-elastic architectures with thermal insulation properties. Another additive strategy for achieving mechanical strength involves the versatile orthogonal surface hybridization of porous silica voxels retains its low thermal conductivity of 19.1 mW m −1 K −1 , flexible compressive recovery strain (85%), and tailored mechanical strength from 71.6 kPa to 1.5 MPa. The printed lightweight high-fidelity objects promise thermal aging mitigation for lithium-ion batteries, providing a thermal management pathway using 3D printed silica objects.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Determining the hydronium pKα at platinum surfaces and the effect on pH-dependent hydrogen evolution reaction kinetics

Electrocatalytic hydrogen evolution reaction (HER) is critical for green hydrogen generation and exhibits distinct pH-dependent kinetics that have been elusive to understand. A molecular-level understanding of the electrochemical interfaces is essential for developing more efficient electrochemical processes. Here we exploit an exclusively surface-specific electrical transport spectroscopy (ETS) approach to probe the Pt-surface water protonation status and experimentally determine the surface hydronium pK a = 4.3. Quantum mechanics (QM) and reactive dynamics using a reactive force field (ReaxFF) molecular dynamics (RMD) calculations confirm the enrichment of hydroniums (H 3 O + * ) near Pt surface and predict a surface hydronium pK a of 2.5 to 4.4, corroborating the experimental results. Importantly, the observed Pt-surface hydronium pK a correlates well with the pH-dependent HER kinetics, with the protonated surface state at lower pH favoring fast Tafel kinetics with a Tafel slope of 30 mV per decade and the deprotonated surface state at higher pH following Volmer-step limited kinetics with a much higher Tafel slope of 120 mV per decade, offering a robust and precise interpretation of the pH-dependent HER kinetics. These insights may help design improved electrocatalysts for renewable energy conversion.

Zhong, Guangyan↗