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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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33 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Ligand Influence on Indium–Sulfide Cluster Formation and Reactivity

An indium–sulfide tetramer ([InMe 2 (SSiMe 3 )] 4 ), which contains reactive silyl and methyl groups, is shown to be an isolable intermediate in cluster synthesis. The reactive groups allow it to act as a synthon in the formation of multinuclear indium–sulfide architectures, evidenced by the crystallization of a coordination polymer ([In 20 S 14 Me 32 (4,4’-bpy) 5 ·5CH 2 Cl 2 ] n ) utilizing In 10 S 7 clusters as nodes. The reaction between trimethylindium (InMe 3 ) and bis­(trimethylsilyl)­sulfide (S­(SiMe 3 ) 2 ) is explored with and without the presence of a ligating bipyridine. In both cases, a sulfide-indium adduct is formed, which slowly converts into a multimetallic complex. Here, the ligand 2,2’-bipyridine (2,2’-bpy) is coordinated to InMe 3 to form the adduct InMe 3 (bpy), which upon addition of sulfide, eliminates tetramethylsilane (TMS) and binds two additional InMe 3 moieties (InMe 2 (bpy)­(μ 3 -SSiMe 3 )­(InMe 3 ) 2 ). When reacted neatly without bipyridine, InMe 3 and S­(SiMe 3 ) 2 form the adduct InMe 3 (S­(SiMe 3 ) 2 ), which subsequently eliminates TMS and intermolecularly associates to yield [InMe 2 (SSiMe 3 )] 4 . Although stable in an inert atmosphere, [InMe 2 (SSiMe 3 )] 4 undergoes facile hydrolysis to yield [InMeS] n when exposed to air. The effect of ligand addition (4,4’-bipyridine (4,4’-bpy)) to [InMe 2 (SSiMe 3 )] 4 is then examined. In every case, it is shown that the presence of the bpy ligand has a profound influence on the resulting structure, as shown by the unexpected formation of a trimer and In 10 S 7 cluster network.

Bell, Colby Seth [Argonne National Laboratory (ANL↗
DOE OSTI2025

Quantifying the Lewis Acidity of Mono-, Di-, and Trivalent Cations in Anhydrous Bis(trifluoromethylsulfonyl)imide Salts

While the bis(trifluoromethylsulfonyl)imide anion (TFSI – ; formula [N(SO 2 CF 3 ) 2 ] – ) has been noted for its practical utility, the use of TFSI – salts as sources of Lewis acidic metal cations for studies of cation-driven tuning effects has not been reported. Here, the effective Lewis acidity of mono-, di-, and trivalent cations (namely, K + , Na + , Li + , Ba 2+ , Ca 2+ , Mg 2+ , Zn 2+ , La 3+ , Y 3+ , Lu 3+ , and Sc 3+ ) in the form of their TFSI – salts is described, along with quantitative comparisons to salts of several other weakly coordinating anions (namely, SO 3 CF 3 – , PF 6 – , and BArF 24 – ). Triphenylphosphine oxide (TPPO) was used as a 31 P NMR probe in titration experiments for quantification of key parameters describing the effective Lewis acidity of the salts in acetonitrile (CH 3 CN) solutions. Notably, the TFSI – salts of di- and trivalent cations were found to display strong binding to TPPO with significant speciation and were found to be quite hygroscopic. Taken together, the measurements demonstrate that TFSI – salts are systematically better/stronger effective Lewis acids than their triflate analogues. And, considering the excellent solubility of TFSI – salts, these materials appear attractive for further use and development in Lewis-acidity-dependent applications, including catalysis and tuning of multimetallic materials.

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

Nanocluster Rearrangement Forms a Family of Ordered Cerium–Titanium Bimetallic Metal–Organic Frameworks with Three Different Nodes, Nanocavities, and Thermal Stabilities

Metal–organic frameworks (MOFs) provide a versatile platform for incorporating multiple metal ions within a single crystalline framework, yet achieving spatial and stoichiometric order in heterometallic nodes remains a synthetic challenge. Building on our previously reported, highly thermally stable Ce/Ti bimetallic MOF NU-3000, we identified and isolated two additional crystalline phases, NU-2998 and NU-2999, that arise from the same Ce/Ti nanocluster precursor under modified solvothermal conditions. Systematic variation of reaction temperature, time, solvent ratio, and modulator concentration directs the assembly of these distinct frameworks. Structural analysis and comprehensive characterization studies reveal that these MOFs each feature an unreported nodal geometry with nanocavities of different sizes. NU-2998 even adopts an unreported topology, denoted nui , that features an elongated pore spanning 4 nm. Together, these findings establish a synthesis route that starts with a nanocluster and ends with a set of bimetallic MOFs, offering a glimpse into the pathway-dependent assembly of multimetallic porous materials. Finally, we evaluated the thermal stability of each additional analogue and compared them to NU-3000, providing further insight into material stability. NU-3000 maintained the highest thermal stability and was evaluated as a catalyst for CO oxidation at elevated temperatures.

bimetallic MOFs↗
DOE OSTI2026

Bayesian Optimization of Catalysis with In-Context Learning

Large language models (LLMs) can perform accurate classification with zero or few examples through in-context learning (ICL), allowing the model to observe query-relevant examples at inference time and eliminating the need for additional weight updates to generalize beyond its original training data. We extend this capability to regression with uncertainty estimation using frozen LLMs (e.g., GPT-4o, Gemini), enabling Bayesian optimization (BO) in natural language without explicit model training or feature engineering. We apply this to materials discovery by representing materials as synthesis and testing procedures for use in natural language prompts. This Bayesian, design-first approach prioritizes optimization toward target material properties before detailed characterization, in contrast to conventional experimental workflows that often emphasize characterization of suboptimal materials. On benchmarks like aqueous solubility and oxidative coupling of methane (OCM), BO-ICL matches or outperforms Gaussian processes. In live experiments on the reverse water–gas shift (RWGS) reaction, BO-ICL identifies multimetallic catalysts that approach equilibrium CO yield within 6 and 10 iterations from a pool of 3,700 and 360,000 candidates, respectively. Our method redefines materials representation and accelerates discovery, with broad applications across catalysis, materials science, and AI.

Calibration↗
DOE OSTI2025

Direct Observation of Phase Change Accommodating Hydrogen Uptake in Bimetallic Nanoparticles

Hydrogen holds great promise as a cleaner alternative to fossil fuels, but its efficient and affordable storage remains a significant challenge. Bimetallic systems, such as Pd and Ni, present a promising option for storing hydrogen. In this study, using the combination of different cutting-edge X-ray and electron techniques, we observed the transformations of Pd–Ni nanoparticles, which initially consist of a NiO-rich shell surrounding a Pd-rich core but undergo a major transformation when they interact with hydrogen. During hydrogen exposure, the Pd core breaks into smaller pockets, dramatically increasing its surface area and enhancing the hydrogen storage capacity, especially in nanoparticles with lower Pd content. The findings provide a deep understanding of the morphological changes at the atomic level during hydrogen storage and contribute to designing cost-effective hydrogen storage using multimetallic systems.

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

Formation of Bimetallic Nanoparticles via Exsolution Using a Reducible Metal Oxide Capping Layer

Bimetallic nanoparticles are promising catalysts that can improve performance in heterogeneous catalysis and solid-state electrochemistry. Exsolution is a useful method for forming such nanoparticles; however, it is limited by the elements present within the host oxide lattice. Here, in this work, we develop and demonstrate a strategy to form bimetallic particles from La 0.5 Sr 0.5 Ti 0.94 Ni 0.06 O 3 (LSTN) exsolution and using a reducible SnO 2 capping layer, expanding the range of elements available for bimetallic nanoparticle formation. Using this capping layer strategy, we formed nickel–tin (Ni 0 –Sn 0 ) bimetallic nanoparticles via exsolution. We used in situ near-ambient pressure X-ray photoelectron spectroscopy to monitor surface chemical changes during exsolution, showing that first, SnO 2 volatilized. This SnO 2 loss exposed the perovskite surface of LSTN to reducing conditions, which induced Ni exsolution, and compounded with SnO 2 reduction led to the formation of bimetallic Ni 0 –Sn 0 particles. To evaluate the associated microstructural evolution, we measured grazing incidence small-angle X-ray scattering (GISAXS), which confirmed the loss of the SnO 2 capping layer, and scattering simulations suggested the formation of bimetallic particles. We confirmed the bimetallic nanoparticle composition and morphology by Auger spectroscopy and scanning transmission electron microscopy. The resulting bimetallic nanoparticles were smaller and more thermally stable than the monometallic Ni counterparts on LSTN. This capping layer and exsolution approach allow synthesizing multimetallic nanoparticles and can be applied to other reducible metal oxides and perovskite hosts, broadening the compositional space for advanced catalytic materials.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Side-On N 2 Binding and Reduction by a Heterotetrametallic Zr 2 Co 2 Cluster

In multimetallic compounds, N 2 typically bridges late transition metals in an end-on (η 1 :η 1 ) fashion while early transition metals often bind N 2 side-on (η 2 ), with the latter resulting in more significant N–N bond elongation. In this work, N 2 fixation is accomplished by using a well-defined scaffold featuring a heterobimetallic combination of Zr and Co. We report a heterotetrametallic Zr 2 Co 2 cluster in which N 2 is bound side-on to the two Co centers and end-on to Zr in a μ 3 -η 1 :η 2 :η 2 binding mode that defies established paradigms for N 2 binding. The heterometallic approach is shown to facilitate catalytic reductive silylation of N 2 with turnover numbers far exceeding those of reported cobalt catalysts.

catalysts↗
DOE OSTI2025

Leveraging data mining, active learning, and domain adaptation for efficient discovery of advanced oxygen evolution electrocatalysts

Developing advanced catalysts for acidic oxygen evolution reaction (OER) is crucial for sustainable hydrogen production. This study presents a multistage machine learning (ML) approach to streamline the discovery and optimization of complex multimetallic catalysts. Our method integrates data mining, active learning, and domain adaptation throughout the materials discovery process. Unlike traditional trial-and-error methods, this approach systematically narrows the exploration space using domain knowledge with minimized reliance on subjective intuition. Then, the active learning module efficiently refines element composition and synthesis conditions through iterative experimental feedback. The process culminated in the discovery of a promising Ru-Mn-Ca-Pr oxide catalyst. Our workflow also enhances theoretical simulations with domain adaptation strategy, providing deeper mechanistic insights aligned with experimental findings. By leveraging diverse data sources and multiple ML strategies, we demonstrate an efficient pathway for electrocatalyst discovery and optimization. This comprehensive, data-driven approach represents a paradigm shift and potentially benchmark in electrocatalysts research.

Science & Technology - Other Topics↗
DOE OSTI2024

Fractal Nanostructured Solar Selective Surfaces for Next Gen Concentrating Solar Power (Final Report)

This project reports a novel coating with enhanced solar absorptance and reduced thermal emittance with high efficiency at elevated temperature for next-generation concentrated solar power (CSP) plants, with targeted operating temperatures around 750°C. Highly textured single and multimetallic oxide coatings were electrodeposited onto Inconel substrate by systematically varying the composition and process parameters. The optimized coating exhibited micro-to-nano structures designed to match the wavelengths in the visible region of the solar spectrum. These structures facilitate resonant absorption of solar radiation, significantly boosting solar absorption and accommodating thermal stress during high temperature exposure. A high solar absorptance exceeding 0.985 and a low thermal emittance below 0.5, yielding a thermal efficiency near 95%, was achieved for the optimized coatings without any anti-reflective overcoat, that remained robust after 750 h of isothermal exposure to 750°C in air. The coatings are also robust to severe mechanical and environmental stressors. The innovative approach presented in this study demonstrates the potential for tailoring air-stable solar absorber coatings to achieve high absorption, low emittance, and excellent high-temperature endurance, meeting the rigorous demands of next-generation CSP systems. A technoeconomic analysis reveals the economic advantage of the coatings for Gen3 CSP installations in different geographical zones globally.

14 SOLAR ENERGY↗
DOE OSTI2024

Conversion of Syngas to Light Olefins and Oxygenates using Multi-Functional Catalysts

This report describes our effort in developing catalysts for the conversion of syngas to light olefins and oxygenates. We have developed a series of metal/zeolite catalysts and tested their activity towards the conversion of syngas to light olefins. Light olefins produced in our case mostly comprised of C 2 /C 3 . A series of multimetallic catalyst also synthesized and their performance was evaluated for the conversion of syngas to the production of oxygenates. In case of oxygenates, our specific focus was to maximize the selectivity of C 2+ oxygenates which is a precursor for fuel or can be used as high value chemicals. In this direction, we have identified several Rh based catalysts that are specifically shows superior activity towards oxygenates formation.

10 SYNTHETIC FUELS↗
NASA NTRS1977

Corrosion inhibitors for solar heating and cooling systems

Problems dealing with corrosion and corrosion protection of solar heating and cooling systems are discussed. A test program was conducted to find suitable and effective corrosion inhibitors for systems employing either water or antifreeze solutions for heat transfer and storage. Aluminum-mild-steel-copper-stainless steel assemblies in electrical contact were used to simulate a multimetallic system which is the type most likely to be employed. Several inhibitors show promise for this application.

Humphries, T. S.↗
NASA NTRS1978

Corrosion inhibitors for solar heating and cooling systems

Inhibitors which appeared promising in previous tests and additional inhibitors including several proprietary products were evaluated. Evaluation of the inhibitors was based on corrosion protection afforded an aluminum-mild steel-copper-stainless steel assembly in a hot corrosive water. Of the inhibitors tested two were found to be effective and show promise for protecting multimetallic solar heating systems.

Humphries, T. S.↗
NASA NTRS1980

Ohmic contact to GaAs semiconductor

Multimetallic layers produce stable, low-resistance contacts for p-type GaAs and p-type GaAlAs devices. Contacts present no leakage problems, and their series resistance is too small to measure at 1 Sun intensity. Ohmic contacts are stable and should meet 20-year-life requirement at 150 C for GaAs combined photothermal/photovoltaic concentrators.

Hovel, H. J.↗
NASA NTRSDate not supplied

Large Scale and Multi-Alloy Rocket Engine Component Development using Various Metal Additive Manufacturing Techniques

The NASA Marshall Space Flight Center (MSFC) has been involved with various forms of metallic additive manufacturing (AM) for use in liquid rocket engine component design, development, and testing since 2010. These AM techniques have been demonstrated to significantly reduce hardware cost, shorten fabrication schedules, increase reliability by reducing the number of joints, and improve hardware performance by allowing fabrication of designs not feasible by conventional means. The focus at the NASA MSFC for these metal additive manufacturing techniques include laser powder-bed fusion (L-PBF), blown powder directed energy deposition (DED), arc-based deposition, and Laser Wire Direct Closeout (LWDC). A variety of components have been evaluated and tested including thrust chamber injectors, injector components such as faceplates, regeneratively-cooled combustion chambers, regeneratively-cooled nozzles, gas generator and preburner hardware, and augmented spark igniters. To support these component applications in harsh environments, NASA has advanced a variety of “standard” additive manufacturing alloys such as those in the superalloy-family and also evolved new alloys including GRCop-84, GRCop-42, NASA HR-1, and JBK-75. The purpose of this presentation is to discuss the various component programs at the NASA MSFC using AM to develop, fabricate, and test combustion devices hardware and the evolution of the new additive alloys. One of these projects that will be highlighted is Rapid Analysis and Manufacturing Propulsion Technology (RAMPT), which includes new process development for large scale AM components, multi-metallic AM components, including unique component designs using additive manufacturing. Additional information will be provided on the development of other components, hot-fire testing, post-processing of AM techniques including surface enhancements (polishing) techniques, material and process characterization, future development programs, and dissemination of data to industry partners.

Additive Manufacturing↗