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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Engineering Biomolecular Self–Assembly at Solid–Liquid Interfaces

Biomolecular self–assembly is a key process used by life to build functional materials from the “bottom up.” In the last few decades, bioengineering and bionanotechnology have borrowed this strategy to design and synthesize numerous biomolecular and hybrid materials with diverse architectures and properties. However, engineering biomolecular self–assembly at solid–liquid interfaces into predesigned architectures lags the progress made in bulk solution both in practice and theory. Here, recent achievements in programming self–assembly of peptides, proteins, and peptoids at solid–liquid interfaces are summarized and corresponding applications are described. Recent advances in the physical understandings of self–assembly pathways obtained using in situ atomic force microscopy are also discussed. Furthermore, these advances will lead to novel strategies for designing biomaterials organized at and interfaced with inorganic surfaces.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Tuning Surface Acidity of Mixed Conducting Electrodes: Recovery of Si‐Induced Degradation of Oxygen Exchange Rate and Area Specific Resistance

Abstract Metal oxides are an important class of functional materials, and for many applications, ranging from solid oxide fuel/electrolysis cells, oxygen permeation membranes, and oxygen storage materials to gas sensors (semiconducting and electrolytic) and catalysts, the interaction between the surface and oxygen in the gas phase is central. Ubiquitous Si‐impurities are known to impede this interaction, commonly attributed to the formation of glassy blocking layers on the surface. Here, the surface oxygen exchange coefficient ( k chem ) is examined for Pr 0.1 Ce 0.9 O 2‐δ (PCO), a model mixed ionic electronic conductor, via electrical conductivity relaxation measurements, and the area‐specific resistance (ASR) by electrochemical impedance spectroscopy. It is demonstrated that even low silica levels, introduced by infiltration, depress k chem by a factor 4000, while the ASR increases 40‐fold and we attribute this to its acidity relative to that of PCO. The ability to fully regenerate the poisoned surface by the subsequent addition of basic Ca‐ or Li‐species is further shown. This ability to not only recover Si‐poisoned surfaces by tuning the relative surface acidity of an oxide surface, but subsequently outperform the pre‐poisoned response, promises to extend the operating life of materials and devices for which the catalytic oxygen/solid interface reaction is central.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2025

Orientation Control in Epitaxial PdO Thin Films Grown on MgO (001) – Role of Oxygen Chemical Potential

Control of crystal orientations in thin films of functional materials allowsedictive tuning of their strain states, electronic properties, and surface chemical reactivity. Here, conditions for orientation control in epitaxial PdO films are investigated. Due to its tetragonal structure, PdO can form two orientational relationships with the MgO (001). It is shown that, under an oxygen-rich environment provided by oxygen-plasma-assisted molecular beam epitaxy, both (00l)- and (100)-oriented PdO domains form on MgO (001). Subsequent thermal annealing in a vacuum promotes film restructuring to a predominantly (100)-oriented PdO with improved crystallinity. Ab initio calculations reveal that the (001) orientation has lower strain energy but weaker interfacial interactions and serves as an oxygen vacancy sink, whereas the (100) orientation benefits from significantly stronger MgO─PdO bonding. Consequently (100)-oriented domains become favored under oxygen-poor conditions. A mechanism is proposed whereby vacuum annealing drives orientation transformation by generating oxygen vacancies that destabilize the (001) domains and promote (100) ordering. These findings deepen the understanding of how oxygen content impacts interfacial stability and reorganization, thereby offering a route to tune domain orientations in oxide thin films.

36 MATERIALS SCIENCE↗
DOE OSTI2025

A General Strategy for Bandgap Engineering Via Anion‐Lattice Doping in High‐Entropy Oxides

Bandgap engineering is a critical tool for tailoring the electronic properties of functional materials, traditionally achieved by modifying the cation sublattice. Here, a generalizable strategy is introduced that leverages facile anion-lattice doping in high entropy materials to modulate the bandgap in high-entropy metal oxides (HEMOs). By incorporating nitrogen into a single-phase high-entropy metal oxide/nitride (HEMO:HEMN) solid solution, a substantial bandgap reduction is achieved from 3.55 eV (HEMO) to ≈2.46 eV (HEMO:HEMN), significantly enhancing electronic conductivity. Unlike conventional bandgap tuning approaches that rely on cation substitution or heterojunction formation, this method exploits anion-mediated entropy stabilization, enabling uniform bandgap narrowing across the entire solid solution. This anion-lattice engineering strategy is broadly applicable to high-entropy systems, providing a new pathway for designing energy materials with tailored electronic properties. The resulting HEMO:HEMN solid solution exhibits a tenfold increase in capacitance and capacity compared to HEMO in supercapacitor and lithium-ion battery tests, demonstrating the transformative potential of anion-driven bandgap modulation for next-generation energy storage and conversion technologies.

energy storage↗
DOE OSTI2020

A Comprehensive Review on the Development of Solid–State Metal–Air Batteries Operated on Oxide–Ion Chemistry

The recently developed solid oxide metal–air redox battery (SOMARB) operating on oxide-ion chemistry represents an emerging and promising energy storage technology, which is well suited for managing grid stability and efficiently harvesting renewable energy. Compared to widely reported metal–air batteries operating on liquid-phase alkali-ion or alkaline chemistries, the SOMARB uniquely features a direct reduction of the high concentration of O 2 molecules in the gas phase without invoking the detrimental formation of a diffusion-blocking oxide phase on the surface of the oxygen electrode. A typical SOMARB is composed of a reversible solid oxide cell (RSOC) and an energy storage unit (ESU), which is capable of storing a high capacity of energy at high power without safety concerns. In this article, the SOMARB concept birth and development are reviewed and discussed with the fundamental differences separating it from other types of metal–air batteries, along with the challenges and opportunities around commercialization. Particular focus is placed on the functional materials tailored for ESU and RSOC applications, including recent experimental and computational efforts to boost the redox activity of Fe-based ESU materials and the performance of intermediate temperature RSOCs. Lastly, candid opinions are offered on the challenges and opportunities facing the future development of SOMARBs toward large-scale energy storage applications.

08 HYDROGEN↗
DOE OSTI2023

Advances in Regioselective Functionalization of Endohedral Metallofullerenes †

Comprehensive Summary Endohedral metallofullerenes (EMFs) are a family of molecules with metal clusters or ions encapsulated inside a fullerene cage. Their unique structures provide a powerful interface for organic chemists to manipulate metal elements. Over a decade ago, many reactions on empty fullerenes were adopted for EMFs, resulting in a series of reactions that are well‐established and reviewed in the literature. In recent years, new topics have emerged in EMF chemistry. First, new addition reactions were developed, notably some that are not based on known empty‐fullerene reactions. Second, considerable progress has been made on regioselective multi‐additions on EMFs. Finally, EMFs have been covalently conjugated with fullerene C 60 to form functional materials. This Recent Advances article will focus on these new developments and discuss their implication for future directions of EMFs.

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

Probing the Kinetic Origin of Varying Oxidative Stability of Ethyl- vs. Propyl-spaced Amines for Direct Air Capture

Amine-based adsorbents are promising for direct air capture of CO 2 , yet oxidative degradation remains a key unmitigated risk hindering wide-scale deployment. Borrowing wisdom from the basic auto-oxidation scheme, insights are gained into the underlying degradation mechanisms of polyamines by quantum chemical, advanced sampling simulations, adsorbent synthesis, and accelerated degradation experiments. The reaction kinetics of polyamines are contrasted with that of typical aliphatic polymers and they elucidate for the first time the critical role of aminoalkyl hydroperoxide decomposition in the oxidative degradation of amino-oligomers. The experimentally observed variation in oxidative stability of polyamines with different backbone structures is explained by the relationship between the local chemical structure and the free energy barrier of aminoalkyl hydroperoxide decomposition, suggesting that its energetics can be used as a descriptor to screen and design new polyamines with improved stability. In conclusion, the developed computational capability sheds light on radical-induced degradation chemistry of other organic functional materials.

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

Polymer Waste Valorization into Advanced Carbon Nanomaterials for Potential Energy and Environment Applications

The rise in universal population and accompanying demands have directed toward an exponential surge in the generation of polymeric waste. The estimate predicts that world-wide plastic production will rise to ≈590 million metric tons by 2050, whereas 5000 million more tires will be routinely abandoned by 2030. Handling this waste and its detrimental consequences on the Earth's ecosystem and human health presents a significant challenge. Converting the wastes into carbon-based functional materials viz. activated carbon, graphene, and nanotubes is considered the most scientific and adaptable method. Herein, this world provides an overview of the various sources of polymeric wastes, modes of build-up, impact on the environment, and management approaches. Update on advances and novel modifications made in methodologies for converting diverse types of polymeric wastes into carbon nanomaterials over the last 5 years are given. A remarkable focus is made to comprehend the applications of polymeric waste-derived carbon nanomaterials (PWDCNMs) in the CO 2 capture, removal of heavy metal ions, supercapacitor-based energy storage and water splitting with an emphasis on the correlation between PWDCNMs' properties and their performances. In conclusion, this review offers insights into emerging developments in the upcycling of polymeric wastes and their applications in environment and energy.

36 MATERIALS SCIENCE↗
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 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 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↗
DOE OSTI2021

Pushing Cu uphill of the volcano curve: Impact of a WC support on the catalytic activity of copper toward the hydrogen evolution reaction

Here, the adsorption of atomic H and H 2 on copper mono- and submonolayers supported on hexagonal WC(0001) surfaces has been investigated using density functional theory with the Perdew–Burke–Ernzerhof exchange correlation functional and D2 van der Waals corrections. Results evidence the impact of the termination of the carbide substrate on fundamental properties of Cu adatoms, and, hence, on the stability of molecular and atomic hydrogen, defining copper's catalytic activity for hydrogen evolution reaction. Using H adsorption energy as a descriptor, catalytic activity of Cu adlayers for hydrogen evolution reaction was estimated using traditional volcano curves and a curve, obtained at low hydrogen coverage. Obtained results evidence that copper adlayers supported on the WC may present a viable low-cost alternative to noble metal-based catalysts, with improved catalytic activity compared to that of copper. This, potentially, can be a useful basis for designing and developing novel functional materials with predetermined catalytic properties.

08 HYDROGEN↗
DOE OSTI2025

Integrated CO 2 capture and hydrogenation in presence of Ru–Na 2 ZrO 3 : An in-situ study

Integrated CO 2 capture and conversion (ICCC) by hydrogenation is a promising strategy to utilize carbon dioxide and this work add to the effort to elucidate the catalytic hydrogenation mechanism using Ru based dual functional materials (DFM). Ru-Na 2 ZrO 3 DFMs, obtained through different wet methods, were evaluated for the first time and the relationship between Ru and support systematically investigated. The thermally stable and cyclable Ru-Na 2 ZrO 3 -a (obtained without filtration step) exhibited CO 2 conversion of 80% and a higher yield of CO at 400°C compared to previously tested DFM, while the Na depleted/Zr rich Ru-Na 2 ZrO 3 -b resulted in 90% selectivity to CH 4 with yield of 1.11 mmol/g at the same temperature. The in-situ experiments have provided conclusive evidence showing that CO 2 hydrogenation on the two Ru DFMs is fundamentally different. In Ru-Na 2 ZrO 3 -a, the monoclinic Na 2 ZrO 3 support acted as the active centre (not as promoter) for CO 2 bridging binding and hydrogenation to CH 4 at the metal-support interface through associative formate pathway with limited further reduction to methane due to lack of H 2 spillover from the small and well dispersed Ru NPs, which results in CO desorption. Conversely, abundant clusters of larger Ru NPs in Ru-Na 2 ZrO 3 -b, led to CH 4 production due to co-existent Ru on-top direct dissociation of CO 2 (preferential) and monodentate formate adsorption and further methanation. Alkali zirconates doped metals, and their synthesis method could thus play a crucial role in designing tuneable heterogeneous catalysis in C 1 chemistry, which could significantly benefit the environment by lowering CO 2 levels, encouraging cleaner industrial practices, supporting a circular economy, and converting waste CO 2 into valuable products.

36 MATERIALS SCIENCE↗