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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Coordination Polymer Electrocatalysts Enable Efficient CO‐to‐Acetate Conversion

Abstract Upgrading carbon dioxide/monoxide to multi‐carbon C 2+ products using renewable electricity offers one route to more sustainable fuel and chemical production. One of the most appealing products is acetate, the profitable electrosynthesis of which demands a catalyst with higher efficiency. Here, a coordination polymer (CP) catalyst is reported that consists of Cu(I) and benzimidazole units linked via Cu(I)‐imidazole coordination bonds, which enables selective reduction of CO to acetate with a 61% Faradaic efficiency at −0.59 volts versus the reversible hydrogen electrode at a current density of 400 mA cm −2 in flow cells. The catalyst is integrated in a cation exchange membrane‐based membrane electrode assembly that enables stable acetate electrosynthesis for 190 h, while achieving direct collection of concentrated acetate (3.3 molar) from the cathodic liquid stream, an average single‐pass utilization of 50% toward CO‐to‐acetate conversion, and an average acetate full‐cell energy efficiency of 15% at a current density of 250 mA cm −2 .

Luo, Mingchuan↗
DOE OSTI2023

A Superconducting Micro-Magnetometer for Quantum Vortex in Superconducting Nanoflakes

Superconducting quantum interferometer device (SQUID) plays a key role in understanding electromagnetic properties and emergent phenomena in quantum materials. The technological appeal of SQUID is that its detection accuracy for the electromagnetic signal can precisely reach the quantum level of a single magnetic flux. However, conventional SQUID techniques normally can only be applied to a bulky sample and do not have the capability to probe the magnetic properties of micro-scale samples with small magnetic signals. Here, in this paper, it is demonstrated that, based on a specially designed superconducting nano-hole array, the contactless detection of magnetic properties and quantized vortices in micro-sized superconducting nanoflakes is realized. An anomalous hysteresis loop and a suppression of Little–Parks oscillation are observed in the detected magnetoresistance signal, which originates from the disordered distribution of the pinned vortices in Bi 2 Sr 2 CaCu 2 O 8+δ . Therefore, the density of pinning centers of the quantized vortices on such micro-sized superconducting samples can be quantitatively evaluated, which is technically inaccessible for conventional SQUID detection. The superconducting micro-magnetometer provides a new approach to exploring mesoscopic electromagnetic phenomena of quantum materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Electrically Reconfigurable Liquid Metal Nanophotonic Platform for Color Display and Imaging

Dynamically tunable optical materials and device architectures are essential for future photonic technologies, yet conventional solid metals lack the intrinsic tunability required for advanced functionalities. Gallium-based liquid metals (LMs) present an appealing alternative thanks to their distinctive mechanical and optical properties; however, their practical integration in tunable photonic elements remains largely unexplored. Here, in this study, an electrochemically controlled nanophotonic platform is demonstrated that integrates a dynamically reconfigurable LM ground plane with gold nanoantenna arrays within a microfluidic system, enabling precise and reversible modulation of optical resonances across the visible to mid-infrared spectral ranges. By employing moderate operational voltages (1.5–3.0 V), real-time tuning of high-resolution structural color patterns is achieved through nanoscale control of the interfacial gap between the LM and Au nanoantennas. This innovative platform facilitates electrically programmable, high-contrast color patterns suitable for dynamic optical displays, secure anti-counterfeiting labels, and imaging applications. Additionally, this platform enables tunable mid-infrared spectral responses, which may be utilized for chemical and biological sensing applications. This versatile integrated LM-based nanophotonic platform opens new paths toward multifunctional, actively tunable/reconfigurable photonic device and system technologies.

Imaging↗
DOE OSTI2023

Tuning Phase Purity in Chiral 2D Perovskites

The introduction of chiral organic spacers in low-dimensional metal-halide perovskites triggers chiroptical activity, which is appealing for spintronic applications. However, a comprehensive understanding of structure formation and the ability to control phase purity in such materials have yet to be developed. Herein, the impact of processing conditions on the phase purity, microstructure, and chiroptical properties of chiral 2D perovskites is explored. The anisotropic emergence of a 1D perovskite inside the 2D matrix and its dependence on the organic cation chirality, solvent, and thermal annealing conditions are shown. By controlling these parameters, the in-plane conductivity of the films is nearly doubled. Furthermore, it is demonstrated, for the first time, that solvent choice and the spatial configuration of the organic cation can have an impact on the residual lattice strain and the energetic disorder of the system. The fundamentals presented here can help to improve the film deposition methods for low-dimensional chiral perovskites, offering strategies to control phase purity.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Volumetric Additive Manufacturing of Dormant Catalytic Chemistries to Generate Silicone Micro‐ and Millifluidic Devices and Instant Molds

Tomographic volumetric additive manufacturing (T‐VAM) rapidly prints solid objects within minutes, accessing photochemistries that are traditionally challenging for layer‐based additive manufacturing methods. This includes high‐viscosity materials, air‐free chemistries, and solid‐state systems. Catalytic chemistries are appealing as a pathway to engineering advanced materials, including tough thermosets, silicone elastomers, and complex block copolymers. However, photoactivated dormant catalytic chemistries, where the catalyst irreversibly activates upon exposure to light, are incompatible with typical tomographic VAM approaches. To address this limitation, a zero‐dose optimization strategy is devised to preserve dormant catalysts in desired regions by keeping them unexposed to light. VAM printed micro‐ and millifluidic devices and instant molds are successfully produced within minutes in silicones polymerized using photoactivated dormant platinum photohydrosilylation catalysts. The printed channels are programmed to be 500 and 2500 µm for the micro‐ and millifluidic devices, and print fidelity is assessed by X‐ray computed tomography. This work demonstrates the potential of zero‐dose optimization to expand the range of chemistries accessible for VAM, enabling the rapid fabrication of complex devices.

Additive Manufacturing↗
DOE OSTI2018

Beyond Insertion for Na‐Ion Batteries: Nanostructured Alloying and Conversion Anode Materials

Abstract Sodium‐ion technology has the potential to become the next generation of low cost and environmentally friendly electrochemical energy storage system for grid‐level applications. The low cost and abundant raw materials employed in sodium cells have driven the recent increasing interest in sodium‐ion batteries (SIBs), which appear especially appealing, since manufacturers can use the already existing production technology of lithium‐ion batteries. However, SIBs are still an early stage technology, which requires several issues affecting cell performance to be addressed. Despite the accelerated development of cathode materials, anode materials still require further investigation and optimization to reach high energy density performance. In the pursuit of high capacity anode materials, several alloying‐, conversion‐, and combined conversion–alloying‐based electrodes have been investigated. This review offers a comprehensive overview on the recent progresses toward the realization of “beyond‐insertion” anode materials. The role of nanostructuration with the associated advantages and disadvantages is presented for each class of compounds, combined with the main strategies adopted to improve the electrochemical behavior. Finally, an overview of the challenges and perspectives associated with the development of the next generation of anode materials is presented with a particular focus on the role of the electrolyte solutions and solid/electrolyte interphase.

Zhang, Huang↗
DOE OSTI2019

Boosting Superior Lithium Storage Performance of Alloy-Based Anode Materials via Ultraconformal Sb Coating–Derived Favorable Solid-Electrolyte Interphase

Alloy materials such as Si and Ge are attractive as high-capacity anodes for rechargeable batteries, but such anodes undergo severe capacity degradation during discharge-charge processes. Compared to the over-emphasized efforts on the electrode structure design to mitigate the volume changes, understanding and engineering of the solid-electrolyte interphase (SEI) are significantly lacking. This work demonstrates that modifying the surface of alloy-based anode materials by building an ultraconformal layer of Sb can significantly enhance their structural and interfacial stability during cycling. Combined experimental and theoretical studies consistently reveal that the ultraconformal Sb layer is dynamically converted to Li 3 Sb during cycling, which can selectively adsorb and catalytically decompose electrolyte additives to form a robust, thin, and dense LiF-dominated SEI, and simultaneously restrain the decomposition of electrolyte solvents. Hence, the Sb-coated porous Ge electrode delivers much higher initial Coulombic efficiency of 85% and higher reversible capacity of 1046 mAh g -1 after 200 cycles at 500 mA g -1 , compared to only 72% and 170 mAh g -1 for bare porous Ge. The present finding has indicated that tailoring surface structures of electrode materials is an appealing approach to construct a robust SEI and achieve long-term cycling stability for alloy-based anode materials.

25 ENERGY STORAGE↗
DOE OSTI2022

High-Entropy and Superstructure-Stabilized Layered Oxide Cathodes for Sodium-Ion Batteries

Layered transition metal oxides are appealing cathodes for sodium-ion batteries due to their overall advantages in energy density and cost. But their stabilities are usually compromised by the complicated phase transition and the oxygen redox, particularly when operating at high voltages, leading to poor structural stability and substantial capacity loss. Here, in this study, an integrated strategy combing the high-entropy design with the superlattice-stabilization to extend the cycle life and enhance the rate capability of layered cathodes is reported. It is shown that the as-prepared high-entropy Na 2/3 Li 1/6 Fe 1/6 Co 1/6 Ni 1/6 Mn 1/3 O 2 cathode enables a superlattice structure with Li/transition metal ordering and delivers excellent electrochemical performance that is not affected by the presence of phase transition and oxygen redox. It achieves a high reversible capacity (171.2 mAh g –1 at 0.1 C), a high energy density (531 Wh kg –1 ), extended cycling stability (89.3% capacity retention at 1 C for 90 cycles and 63.7% capacity retention at 5 C after 300 cycles), and excellent fast-charging capability (78 mAh g –1 at 10 C). This strategy would inspire more rational designs that can be leveraged to improve the reliability of layered cathodes for secondary-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2024

A Comprehensive Experimental Study on Microstructure‐Graded Graphite Anodes for Enhancing Fast‐Charging Capability of Lithium‐Ion Batteries

Lithium‐ion batteries with high gravimetric capacity density and improved cycle life performance under fast‐charging conditions are crucial for widespread electric vehicle (EV) adoption. This study investigates how designing graphite anode microstructure, specifically porosity, and particle‐size gradients, improves lithium‐ion (Li + ) transport during fast‐charging conditions. Three‐layered graphite anodes with varying porosity (24%, 36%, 46%) and particle size gradients (3, 5, 10 μm) were compared to a conventional single‐layered electrode in half‐cell configurations. At room temperature and high discharge rate (2C), both gradient structures showed significantly enhanced capacity retention (80% and 67% vs. 50%) compared to the conventional electrode, highlighting the effectiveness of microstructure engineering for fast charging. The study also investigated the temperature's impact on cycle life. After 200 cycles at 2°C and 45°C, all gradient structures demonstrated superior capacity retention (≈80%) compared to the conventional electrode (35%), suggesting the gradients mitigate degradation rate at high temperatures. Electrochemical impedance spectroscopy confirmed superior Li+ diffusion and lower resistivity in gradient electrodes. Simulations explored the influence of gradient profiles on reaction kinetics across the electrode thickness. Overall, this research demonstrates that the fast‐charging capability of graphite electrodes can be greatly enhanced by engineering the electrode microstructure, thereby making EV technology more accessible and appealing.

Ahmadi, Soma↗
DOE OSTI2019

Atomically Dispersed Molybdenum Catalysts for Efficient Ambient Nitrogen Fixation

Abstract NH 3 synthesis by the electrocatalytic N 2 reduction reaction (NRR) under ambient conditions is an appealing alternative to the currently employed industrial method—the Haber–Bosch process—that requires high temperature and pressure. We report single Mo atoms anchored to nitrogen‐doped porous carbon as a cost‐effective catalyst for the NRR. Benefiting from the optimally high density of active sites and hierarchically porous carbon frameworks, this catalyst achieves a high NH 3 yield rate (34.0±3.6 μg h −1 mg cat. −1 ) and a high Faradaic efficiency (14.6±1.6 %) in 0.1 m KOH at room temperature. These values are considerably higher compared to previously reported non‐precious‐metal electrocatalysts. Moreover, this catalyst displays no obvious current drop during a 50 000 s NRR, and high activity and durability are achieved in 0.1 m HCl. The findings provide a promising lead for the design of efficient and robust single‐atom non‐precious‐metal catalysts for the electrocatalytic NRR.

Han, Lili↗
DOE OSTI2021

Kinetic Limitations in Single‐Crystal High‐Nickel Cathodes

Abstract High‐nickel cathodes attract immense interest for use in lithium‐ion batteries to boost Li‐storage capacity while reducing cost. For overcoming the intergranular‐cracking issue in polycrystals, single‐crystals are considered an appealing alternative, but aggravating concerns on compromising the ionic transport and kinetic properties. We report here a quantitative assessment of redox reaction in single‐crystal LiNi 0.8 Mn 0.1 Co 0.1 O 2 using operando hard X‐ray microscopy/spectroscopy, revealing a strong dependence of redox kinetics on the state of charge (SOC). Specifically, the redox is sluggish at low SOC but increases rapidly as SOC increases, both in bulk electrodes and individual particles. The observation is corroborated by transport measurements and finite‐element simulation, indicating that the sluggish kinetics in single‐crystals is governed by ionic transport at low SOC and may be alleviated through synergistic interaction with polycrystals integrated into a same electrode.

Ge, Mingyuan↗
DOE OSTI2021

Mediated Inner‐Sphere Electron Transfer Induces Homogeneous Reduction of CO 2 via Through‐Space Electronic Conjugation**

Abstract The electrocatalytic reduction of CO 2 is an appealing method for converting renewable energy sources into value‐added chemical feedstocks. We report a co‐electrocatalytic system for the reduction of CO 2 to CO comprised of a molecular Cr complex and dibenzothiophene‐5,5‐dioxide (DBTD) as a redox mediator, which achieves high activity (TOF=1.51–2.84×10 5 s −1 ) and quantitative selectivity. Under aprotic or protic conditions, DBTD produces a co‐electrocatalytic response with 1 by coordinating trans to the site of CO 2 binding and mediating electron transfer from the electrode with quantitative efficiency for CO. This assembly is reliant on through‐space electronic conjugation between the π frameworks of DBTD and the bpy fragment of the catalyst ligand, with contributions from dispersive interactions and weak sulfone coordination.

Hooe, Shelby L.↗
DOE OSTI2022

Near‐Room‐Temperature Magnetoelectric Coupling via Spin Crossover in an Iron(II) Complex

Abstract Magnetoelectric coupling is achieved near room temperature in a spin crossover Fe II molecule‐based compound, [Fe(1bpp) 2 ](BF 4 ) 2 . Large atomic displacements resulting from Jahn–Teller distortions induce a change in the molecule dipole moment when switching between high‐spin and low‐spin states leading to a step‐wise change in the electric polarization and dielectric constant. For temperatures in the region of bistability, the changes in magnetic and electrical properties are induced with a remarkably low magnetic field of 3 T. This result represents a successful expansion of magnetoelectric spin crossovers towards ambient conditions. Moreover, the observed 0.3–0.4 mC m −2 changes in the H ‐induced electric polarization suggest that the high strength of the coupling obtained via this route is accessible not just at cryogenic temperatures but also near room temperature, a feature that is especially appealing in the light of practical applications.

Owczarek, Magdalena↗
DOE OSTI2025

Synergistic Tuning of Microstructure and Morphology in Carbon Molecular Sieve Hollow Fibers for Propylene/Propane Separation

Abstract Asymmetric carbon molecular sieve (CMS) hollow fiber membranes with tunable micro‐ and macro‐structural morphologies for energy efficient propylene‐propane separation are reported here. A sub‐glass transition temperature (sub‐Tg) thermal oxidative crosslinking strategy enables simultaneous optimization of the intrinsic molecular sieving properties while also reducing the thickness of the CMS “skin” derived from the 6FDA : BPDA/DAM polyimide precursors. Such synergistic tuning of CMS microstructure and macroscopic morphology of CMS hollow fibers enables significantly increased propylene permeance (reaching 186.5 GPU) while maintaining an appealing propylene/propane selectivity of 13.3 for 50/50 propylene/propane mixed gas feeds. Our findings reveal a more refined and versatile tool than available with previous O 2 ‐doping pretreatments. The advanced approach here should be broadly useful to other polyimide precursors and diverse gas pairs.

Liu, Zhongyun [School of Chemical &amp, Biomolecul↗
DOE OSTI2025

Sub‐5 Ångstrom Porosity Tuning in Calixarene‐Derived Porous Liquids via Supramolecular Complexation Construction

Abstract Sub‐Ångstrom‐level porosity engineering, which is appealing in gas separations, has been demonstrated in solid carbon, polymer, and framework materials but rarely achieved in the liquid phase. In this work, a gas molecular sieving effect in the liquid phase at sub‐5 Ångstrom scale is created via sophisticated porosity tuning in calixarene‐derived porous liquids (PLs). Type II PLs are constructed via supramolecular complexation between the sodium salts of calixarene derivatives and crown ether solvents. The chemical structure variation and assembly behavior of the porous host upon PL construction are monitored by spectroscopy‐, X‐ray‐, and neutron‐scattering techniques. The presence of permanent porosity in calixarene‐derived PLs is verified by pressure swing gas uptake, altered CO 2 physisorption behavior, and molecular simulations. Sub‐5 Ångstrom porosity tuning within the PL phase is achieved by introducing bulky substituted groups on the benzene ring of the calixarene host, which then greatly affects the dynamic motion and transport behavior of CO 2 molecules and the Xe uptake performance. The approach being demonstrated in this work represents a promising pathway to tune and leverage the porosity effect for enhanced gas uptake capacity and selectivity in liquid sorbents.

Li, Errui [Department of Chemistry University of T↗
DOE OSTI2018

Atomically Dispersed Molybdenum Catalysts for Efficient Ambient Nitrogen Fixation

NH 3 synthesis by the electrocatalytic N 2 reduction reaction (NRR) under ambient conditions is an appealing alternative to the currently employed industrial method—the Haber–Bosch process—that requires high temperature and pressure. We report here single Mo atoms anchored to nitrogen-doped porous carbon as a cost-effective catalyst for the NRR. Benefiting from the optimally high density of active sites and hierarchically porous carbon frameworks, this catalyst achieves a high NH 3 yield rate (34.0±3.6 μg NH 3 h -1 mg cat. -1 ) and a high Faradaic efficiency (14.6±1.6 %) in 0.1 m KOH at room temperature. These values are considerably higher compared to previously reported non-precious-metal electrocatalysts. Moreover, this catalyst displays no obvious current drop during a 50 000 s NRR, and high activity and durability are achieved in 0.1 m HCl. The findings provide a promising lead for the design of efficient and robust single-atom non-precious-metal catalysts for the electrocatalytic NRR.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗