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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

An Exceptionally Stable Metal–Organic Framework Constructed from Chelate-Based Metal–Organic Polyhedra

In this paper, we report the rational design and synthesis of a new, water-stable metal-organic framework (MOF), Fe-HAF-1, constructed from supramolecular, Fe3+-hydroxamate-based polyhedra with mononuclear metal nodes. Owing to its chelate-based con-struction, Fe-HAF-1 displays exceptional chemical stability in organic and aqueous solvents over a wide pH range (pH 1-14), including in the presence of 5 M NaOH. Despite the charge-neutrality of the Fe 3+ -tris(hydroxamate) centers, Fe-HAF-1 crystals are negatively charged above pH 4. This unex-pected property is attributed to the formation of defects during crystallization that results in uncoordinated hydroxamate ligands or hydroxide-coordinated Fe centers. The anionic na-ture of Fe-HAF-1 crystals enables selective adsorption of pos-itively charged ions in aqueous solution, resulting in efficient separation of organic dyes and other charged species in a size-selective fashion. Fe-HAF-1 presents a new addition to a small group of chelate-based MOFs and provides a rare framework whose 3D connectivity is exclusively formed by metal-hydroxamate coordination.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Demonstration of Spectral Selectivity of Efficient and Ultrafast GaN/AlGaN-Based Metal–Semiconductor–Metal Ultraviolet Photodiodes

Efficient and ultrafast (aluminum)-gallium-nitride-based metal-semiconductor-metal (Al x )Ga 1–x N ultraviolet photodiodes were implemented to investigate the spectral properties of GaN/AlGaN-based photodetectors. Al composition of the GaN templates were varied from 0-% to 30% to demonstrate the impact of Al mole fraction on the cutoff wavelength of these UV photodiodes. Asymmetric metal contact electrodes were fabricated to optimize the external quantum efficiency without compromising their ultrafast photoresponse. Here, the best performing devices exhibited a peak response of 4 V and an oscilloscope limited temporal pulse width of 61 ps at a 20-V bias with a peak spectral responsivity of 36.5 mA/W at 280 nm.

42 ENGINEERING↗
DOE OSTI2024

Developing Platinum-Group-Metal-Free Catalysts for Oxygen Reduction Reaction in Acid: Beyond the Single Metal Site

This project is to develop M (x) -N-C catalysts with dense multiple metal center (MMC) sites to meet the DOE 2025 activity target of 0.044 mA/cm 2 at 0.9 V IR-free ., as well as other goals such as durability. We have made important contributions to both catalyst development and fundamental understandings of the active sites in M-N-C catalysts in this project. We successfully made M (x) -N-C catalysts with some multiple metal center (MMC) sites by combining ionothermal carbonization with chemical vapor deposition (CVD). These catalysts, however, are not as active as the most active single-atom Fe-N-C catalysts made by the similar CVD process, owing likely to the low site density and the presence of inorganic Fe species such as iron carbides and nanoparticles. The most significant accomplishments we achieved in this project are: (1) we unraveled the formation pathway of Fe-N 4 sites during pyrolysis step-by-step and identified the trans-metalation mechanism, in collaboration with Deborah Myers and her colleagues at Argonne National Laboratory (ANL); (2) inspired by this finding, we pioneered the CVD synthesis of M-N-C catalysts (M = Mn, Fe, and Co), in which the Fe-N-C catalyst by CVD demonstrated an ORR activity of 33 mA/cm 2 at 0.9 V in H 2 -O 2 proton exchange membrane fuel cells (PEMFCs), very close to the ultimate goal of 35 mA/cm 2 of our project. This catalyst is the first Fe-N-C catalyst that contains only D1 sites without the D2 sites; whereas D1 and D2 sites have been always identified by Mossbauer in previous Fe-N-C catalysts. This finding helps to understand what the D1 and D2 sites are and their roles in catalyzing the ORR. (3) by improving the mass transport of the carbon matrix prior to the CVD process, the revised Fe-N-C catalyst made by CVD delivered a maximum power density of 0.53 W/cm 2 in H 2 -air PEMFCs. The improvement strategy was partly inspired by the computational modeling work by Adam Weber from LBNL, the Co-PI of this project, by developing, coding, and exercising a continuum level model of transport phenomena within a PGM-free catalyst layer. The model demonstrated that local resistances combined with limited site density of the PGM-free catalyst can result in limiting currents and poor polarization performance. The model also gave design guidance for impact of ECSA and overall catalyst-layer thickness. However, both Fe-N-C and Co-N-C catalysts developed by CVD showed poor durability in PEMFCS, in comparison with the traditional M-N-C catalysts synthesized via regular pyrolysis process. Consequently, we did not achieve the proposed durability targets. Despite so, we believe the FeNC-CVD catalysts with the poor durability and D1 sites only provides an excellent platform to understand the degradation mechanism of Fe-N-C in PEMFCs, the most important challenge in the development of M-N-C catalysts.

08 HYDROGEN↗
DOE OSTI2025

PowderJet: Spherical metal powder production via multi-orifice droplet-on-demand metal jetting

Leading metal additive manufacturing techniques, such as laser powder bed fusion and directed energy deposition, rely on high-quality spherical metal powders. However, traditional powder production methods like gas atomization face limitations, including low in-spec yield, asphericity, and internal porosity. We introduce PowderJet, a powder production platform that uses electromagnetic pulses to eject liquid metal droplets from a multi-orifice nozzle. Unlike stochastic methods, PowderJet tightly controls powder size, distribution, and purity through a droplet-on-demand approach. We detail the system’s design, operation, and performance using a combined experimental and computational fluid dynamics (CFD) framework. Initial results with Al4008 and Cu110 alloys demonstrate successful production, yielding unsieved aluminum powder batches with a mean diameter of 200 µm and a narrow size distribution (15 µm standard deviation). The produced powders are highly spherical, achieving a roundness > 0.95. PowderJet operates with a small melt volume (3 mL) and supports continuous refilling, enabling production rates between 30 and 140 cm³/hr depending on jetting frequency, number of orifices and particle size. CFD simulations show that future systems could achieve rates exceeding 1000 cm³/hr for particle sizes as small as 40 µm. PowderJet’s high yield of in-spec powder makes it ideal for producing precious or hazardous materials that are inefficient to manufacture using conventional methods. This platform offers a scalable, precise, and efficient solution for producing high-quality powders tailored for advanced manufacturing applications.

Atomization↗
DOE OSTI2020

Breaking Simple Scaling Relations through Metal–Oxide Interactions: Understanding Room-Temperature Activation of Methane on M/CeO 2 (M = Pt, Ni, or Co) Interfaces

The clean activation of methane at low temperatures remains an eminent challenge and a field of competitive research. In particular, on late transition metal surfaces such as Pt(111) or Ni(111), higher temperatures are necessary to activate the hydrocarbon molecule, but a massive deposition of carbon makes the metal surface useless for catalytic activity. However, on very low-loaded M/CeO 2 (M = Pt, Ni, or Co) surfaces, the dissociation of methane occurs at room temperature, which is unexpected considering simple linear scaling relationships. This intriguing phenomenon has been studied using a combination of experimental techniques (ambient-pressure X-ray photoelectron spectroscopy, time-resolved X-ray diffraction, and X-ray absorption spectroscopy) and density functional theory-based calculations. The experimental and theoretical studies show that the size and morphology of the supported nanoparticles together with strong metal–support interactions are behind the deviations from the scaling relations. These findings point toward a possible strategy for circumventing scaling relations, producing active and stable catalysts that can be employed for methane activation and conversion.

03 NATURAL GAS↗
DOE OSTI2020

Direct Identification of Mixed-Metal Centers in Metal–Organic Frameworks: Cu 3 (BTC) 2 Transmetalated with Rh 2+ Ions

Raman spectroscopy was used to establish direct evidence of heterometallic metal centers in a metal–organic framework (MOF). The Cu 3 (BTC) 2 MOF HKUST-1 (BTC 3– = benzenetricarboxylate) was transmetalated by heating it in a solution of RhCl 3 to substitute Rh 2+ ions for Cu 2+ ions in the dinuclear paddlewheel nodes of the framework. In addition to the Cu–Cu and Rh–Rh stretching modes, Raman spectra of (Cu x Rh 1– x ) 3 (BTC) 2 show the Cu–Rh stretching mode, indicating that mixed-metal Cu–Rh nodes are formed after transmetalation. Density functional theory studies confirmed the assignment of a Raman peak at 285 cm –1 to the Cu–Rh stretching vibration. Electron paramagnetic resonance spectroscopy experiments further supported the conclusion that Rh 2+ ions are substituted into the paddlewheel nodes of Cu 3 (BTC) 2 to form an isostructural heterometallic MOF, and electron microscopy studies showed that Rh and Cu are homogeneously distributed in (Cu x Rh 1– x ) 3 (BTC) 2 on the nanoscale.

02 PETROLEUM↗
DOE OSTI2020

The Bonding Nature and Adhesion of Polyacrylic Acid Coating on Li-Metal for Li Dendrite Prevention

The success of polyacrylic acid (PAA) to suppress Li dendrite growth suggests that the mechanical properties of polymer-based coatings, including the modulus, toughness, and interfacial adhesion are important design criteria. However, the measurement of the adhesion of thin PAA, as well as other polymer coatings to the reactive Li-metal anode surface is limited experimentally and challenging computationally. In this paper, a strategy was proposed to estimate the adhesion and delamination of the PAA(polymer)/Li interface, based on the bonding nature at the simpler PAA (oligomer)/Li interfaces using density functional theory calculations. It has been shown that the carboxylic acid groups in PAA reacted strongly with metallic Li, which significantly enhances the interfacial adhesion through the Li–O bonds formation, Li ionization and its incorporation into PAA, and –H or –OH termination of Li after decomposition of the COOH functional group. During delamination, it was found that the most likely PAA delamination route involved breaking partial Li–O bonds and lifting some ionized Li atoms from the Li-metal, especially for the Li atoms that showed a charge closer to +1 or are bonded with two O atoms from PAA. Based on the average bonding energies from PAA(oligomer)/Li interface delamination calculations, the work of separation, W sep , of the PAA(polymer)/Li interface was estimated to be ~1.0 (J/m 2 ). The high W sep of PAA (polymer)/Li was comparable with the Li 2 O/Li interface and higher than Li 2 CO 3 /Li and LiF/Li interfaces. This order correlated well with the areal density of Li–O bonds, which can serve as a descriptor for the interfacial adhesion. Furthermore, this computational approach can be applied to other interfaces with polymer-based coatings.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

A Transferable Force Field for Simulating Adsorption in Metal–Organic Frameworks with Open Metal Sites Based on the 12–6–4 Lennard-Jones Potential

Metal−organic frameworks (MOFs) that contain coordinatively unsaturated open metal sites (OMSs) provide strong host− guest interactions, making them promising sorbents for low-concentration gas adsorption applications such as direct air capture and atmospheric water harvesting. However, accurately modeling host−guest interactions involving OMSs remains challenging for classical force fields (FFs) based on the 12−6 Lennard−Jones (LJ) potential, as the polarization effect of the guest molecule induced by the positively charged OMS is not considered. Here, we introduce an FF based on the 12−6−4 LJ potential, which incorporates charge−induced dipole interactions and is parametrized against a diverse set of host−guest potential energy surfaces (PESs) obtained from density functional theory (DFT). The resulting FF, trained on a generic trimetallic cluster, performs well in both host−guest binding energetics and gas adsorption isotherms across different OMS-containing MOFs, including MOF-74 series and Cu-BTC. These results highlight the excellent transferability of our approach and its potential to enhance the accuracy and robustness of high-throughput MOF discovery workflows, particularly for gas adsorption and separation in large and diverse MOF databases.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Potassium Metal Batteries: Stable Potassium Metal Anodes with an All-Aluminum Current Collector through Improved Electrolyte Wetting (Adv. Mater. 49/2020)

An explorer is kayaking in uncharted territory, representing the exciting scientific pursuit of emerging metal batteries (MBs). Water is flowing smoothly over the jagged rocks, representing dendrite-free metal anodes as well as enhanced electrolyte wetting, both due to geometrical roughness. The electric eels underneath represent potassium-based energy storage, as they utilize potassium and sodium ions for electricity. In article number 2002908, Pengcheng Liu, David Mitlin, and co-workers present a route via improved electrolyte wetting toward stable potassium metal batteries with an all-aluminum current collector.

25 ENERGY STORAGE↗
DOE OSTI2021

Metallaphotoredox: The Merger of Photoredox and Transition Metal Catalysis

The merger of photoredox catalysis with transition metal catalysis, termed metallaphotoredox catalysis, has become a mainstay in synthetic methodology over the past decade. Metallaphotoredox catalysis has combined the unparalleled capacity of transition metal catalysis for bond formation with the broad utility of photoinduced electron- and energy-transfer processes. Photocatalytic substrate activation has allowed the engagement of simple starting materials in metal-mediated bond-forming processes. Moreover, electron or energy transfer directly with key organometallic intermediates has provided novel activation modes entirely complementary to traditional catalytic platforms. Finally, this Review details and contextualizes the advancements in molecule construction brought forth by metallaphotocatalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Opportunities and Challenges of High-Energy Lithium Metal Batteries for Electric Vehicle Applications

Lithium metal batteries have great advantages over state-of-the-art lithium ion batteries in terms of energy density and cost, which present huge opportunities for long-range and low-cost electric vehicles in the future. However, the automotive industry has critical requirements on specific characteristics of battery cells, including but not limited to cycle life, working temperature range, fast discharge–charge capability, volume change, safety, and so on. In this Focus Review, we discuss both the cell- and system-level requirements and challenges of high-energy-density lithium metal batteries for future electrical vehicle applications and highlight some recent key progress in these aspects. Furthermore, our main objective is to identify key strategies on how to solve these challenges and inspire more research and development effort to accelerate the practical applications of lithium metal batteries.

25 ENERGY STORAGE↗
DOE OSTI2025

Growth of Carbon Nanotubes Using Mixed-Metal Catalysts That Include Heavy Refractory Metals as Catalyst Stabilizers

Here, we report new findings from studies of a novel technique to augment the growth of CNTs. In this method, the catalytic metals used for CNT growth are combined with high-melting-point heavy refractory metals, which serve to stabilize the metal catalyst nanoparticles, from which the CNTs nucleate and grow. Our study investigates the combination of an iron catalyst with tungsten and osmium refractory stabilizers. We find that both tungsten and osmium enhance the lifetime of the iron catalyst particles by a factor of approximately two. Tungsten stabilizer resulted in production of CNTs longer by a factor of 1.25 compared to those produced using a pure iron catalyst, while the osmium stabilizer did not significantly affect the ultimate length of the CNTs due to the decreased CNT growth rate with a combined Fe/Os catalyst. These results suggest a possible new route toward producing CNTs with lengths sufficient for materials applications.

Park, Wonjung [Univ. of Tampa, FL (United States)]↗
DOE OSTI2020

Developing high safety Li-metal anodes for future high-energy Li-metal batteries: strategies and perspectives

Developing high-safety Li-metal anodes (LMAs) is extremely important for the application of high-energy Li-metal batteries (LMBs), especially Li–S and Li–O 2 battery systems. However, the notorious Li-dendrite growth problem results in serious safety concerns for any energy storage application. Through a recent combination of interface-based science, nanotechnology-based solutions and characterization methods, the LMA is now primed for a technological boom. In this review, the recent emerging strategies and perspectives on LMAs are summarized, following which the current huge evolution in interfacial chemistry regulation, optimizing electrolyte components, designing a rational ‘host’ for lithium metal, optimizing “solid-state electrolytes” and other emerging strategies for developing high-safety LMAs is highlighted. Furthermore, several state-of-the-art in situ/operando synchrotron-based X-ray techniques for high safety LMB research are introduced. With the further development of LMAs in the future, subsequent application in high energy LMBs is to be expected.

25 ENERGY STORAGE↗