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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Nanoporous weakly coordinating anionic frameworks (Final Technical Report)

Under this award, we synthesized and characterized new weakly coordinating, anionic covalent organic frameworks. The motivation was to expand the class of covalent organic frameworks though the introduction of the first weakly coordinating anionic ones. The significance of the weakly coordinating anionic character of these frameworks is associated with the character of the counter (metal) cations in their pores. Those counter-cations, due to the inability to effectively coordinate to the pore walls, have a “naked”, and thus highly electrophilic, Lewis acidic character. Such properties are expected to translate to a number of interesting physical properties that can be potentially used for a range of energy-relevant applications. One of these applications is gas adsorption, separation, and storage. The electrophilic, Lewis acidic character of the counter-cations are expected to strongly bind to gas molecules entering the pores leading to higher gas sorption capacities. Other applications include heterogeneous catalysis, ion exchange, and solid state ion conduction. Within the project we explored a range of chemical blocks, and tested synthesis conditions to polymerize these building blocks to form the target materials. In particular, we focused on materials with group 15 elements like phosphorus in the oxidation state +5 and the coordination number 6, that have a formal -1 charge. The synthesis of such materials is challenging because its success depends on the absence of residual monomeric and oligomeric side-products in the pores, and the absence of significant framework interpenetration. Crystalline forms of these materials require sufficient reversibility of the polymerization reaction (which is difficult to achieve because group 15 elements like P tend to make strong covalent bonds with neighbored elements), as well as suitable polymerization rates that prevent the formation of kinetically controlled products. We had success with the preparation of anionic porous organic frameworks with anionic building blocks containing P(V)O6 octahedra synthesized through Yamamoto coupling reactions. These materials are non-crystalline because of the irreversible nature of the Yamamoto coupling reaction, but show porosity. The porosity and surface area can be significantly increased by co-reaction with electrostatically neutral co-reactants. Very high porosity and surface areas can be achieved when the materials are washed with hydrochloric acid. This method is commonly used to free products from Yamamoto coupling reactions from by-products. Indeed, this method removed by products from the pores of our materials, however it also led to the hydrolysis of the PO6 octahedra to form pending phosphonic acid groups (-PO3H)-groups in the frameworks (PA-POFs) which was actually not desired. Nonetheless, these materials showed high CO2 sorption capacities. In addition, they show extremely high (actually record) sorption capacities for the removal of a range of common micropollutants such as bisphenol A (BPA) and 4-nitrophenol in water. BPA is a wide-spread organic pollutant and a known endocrine disruptor. The maximum adsorption capacity of BPA at equilibrium is found to be as high as 3,366 mg g-1 by Langmuir adsorption model, which is more than 10 times greater than peer materials. The polymer also rapidly removes various other organic micropollutants with more than 90% removal efficiencies. In addition, the PA-POF material can be regenerated at least five times by mild washing using methanol without significant loss in removal efficiency. This is significant advantage over commonly used activated carbon materials (that are in Brita water faucet filters, for example). Comparison studies showed that only materials with the phosphonate groups show extreme sorption although the number of PA group is actually small according to solid state NMR and EDX data. More research would be needed to investigate why this is (a possibility is that the phosphonate groups have a multiplying effect in which a PA-induced initial adsorption leads to the adsorption of much more adsorbate). The extreme sorption capabilities can also be visually seen when colored adsorbates such as 4-nitrophenol are used, as the adsorption of the nitrobenzene leads to the decoloration of the solution. We have produced three short videos that illustrate the sorption capabilities compared to two peer materials (activated carbon from dismantled Brita water filters, and a electrostatically neutral, chemically related, porous organic polymer, respectively).

36 MATERIALS SCIENCE↗
DOE OSTI2022

Templated encapsulation of platinum-based catalysts promotes high-temperature stability to 1,100 °C

Stable catalysts are essential to address energy and environmental challenges, especially for applications in harsh environments (for example, high temperature, oxidizing atmosphere and steam). In such conditions, supported metal catalysts deactivate due to sintering-a process where initially small nanoparticles grow into larger ones with reduced active surface area-but strategies to stabilize them can lead to decreased performance. In this work, we report stable catalysts prepared through the encapsulation of platinum nanoparticles inside an alumina framework, which was formed by depositing an alumina precursor within a separately prepared porous organic framework impregnated with platinum nanoparticles. These catalysts do not sinter at 800 °C in the presence of oxygen and steam, conditions in which conventional catalysts sinter to a large extent, while showing similar reaction rates. Extending this approach to Pd-Pt bimetallic catalysts led to the small particle size being maintained at temperatures as high as 1,100 °C in air and 10% steam. This strategy can be broadly applied to other metal and metal oxides for applications where sintering is a major cause of material deactivation.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Ester-Linked Crystalline Covalent Organic Frameworks

Ester-linked, crystalline, porous covalent organic frameworks (COFs) have been synthesized and structurally characterized. Transesterification reactions between ditopic 2-pyridinyl aromatic carboxylates and tri- or tetratopic phenols gave the corresponding ester-linked COFs. They crystallize as 2D structures in kgm (COF-119) and hcb (COF-120, 121, 122) topologies with surface areas of up to 2092 m 2 /g. Notably, crystalline COF-122 comprises edges spanning over 10 phenylene units, an aspect that had only been achieved in metal-organic frameworks. Finally, this work expands the scope of reticular chemistry to include, for the first time, crystalline ester-linked COFs related to common polyesters.

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

Porous Materials for Water Purification

Water pollution is a growing threat to humanity due to the pervasiveness of contaminants in water bodies. Significant efforts have been made to separate these hazardous components to purify polluted water through various methods. However, conventional remediation methods suffer from limitations such as low uptake capacity or selectivity, and current water quality standards cannot be met. Recently, advanced porous materials (APMs) have shown promise in improved segregation of contaminants compared to traditional porous materials in uptake capacity and selectivity. These materials feature merits of high surface area and versatile functionality, rendering them ideal platforms for the design of novel adsorbents. Here, this Review summarizes the development and employment of APMs in a variety of water treatments accompanied by assessments of task-specific adsorption performance. Finally, we discuss our perspectives on future opportunities for APMs in water purification.

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

A Review on Direct Air Capture of Carbon Dioxide: Sorbent Materials, Process Engineering, Industrial Scale-Up, and Future Perspectives

The relentless accumulation of anthropogenic greenhouse gases has driven atmospheric carbon dioxide concentrations to approximately 426 ppm, necessitating the aggressive deployment of negative-emission technologies to achieve net zero by 2050. Direct air capture (DAC) offers a scalable, location-independent approach to atmospheric carbon removal; however, it is fundamentally constrained by the significant thermodynamic barriers associated with capturing CO 2 from ultradilute ambient conditions, requiring minimum thermodynamic energy inputs substantially higher than those for postcombustion point sources. This comprehensive review critically examines the technological landscape of DAC, focusing on the interdependent triad of sorbent material design, contactor engineering, and regeneration thermodynamics. We evaluate the fundamental boundaries of adsorption, emphasizing that an optimal adsorption enthalpy and isosteric heat of adsorption must balance the high CO 2 uptake capacity with the energetic penalties of sorbent regeneration. A systematic, comparative analysis of state-of-the-art sorbents is presented, encompassing mesoporous silicas, zeolites, carbon-based materials (CBMs), metal−organic frameworks (MOFs), porous organic polymers (POPs), and polymeric membranes. Special attention is devoted to surface functionalization strategies, particularly amine grafting and impregnation, which transition capture mechanisms from physisorption to chemisorption to enhance selectivity under ambient moisture and low partial pressures. Furthermore, we assess the operational merits of various reactor configurations, including gas−solid, gas−liquid, and membrane contactors, alongside regeneration cycles such as temperature, vacuum, pressure, and moisture swing adsorption. Finally, the review bridges fundamental materials science with industrial application by chronicling the scale-up milestones of pioneering entities and providing a strategic roadmap for advancing DAC technology readiness levels toward global deployment.

Adsorption↗
DOE OSTI2020

Hydrogen-Bonded Organic Frameworks: A Rising Class of Porous Molecular Materials

Hydrogen-bonded organic frameworks (HOFs) are a class of porous molecular materials that rely on the assembly of organic building blocks by means of hydrogen-bonding interactions to form two-dimensional (2D) and three-dimensional (3D) crystalline networks. The reversible nature of the hydrogen-bond formation endows HOFs with the attributes of solution processability and simple regeneration. High-quality single crystals of HOFs can be grown easily for unambiguous superstructure determination by single-crystal X-ray diffraction, which is crucial for the elucidation of superstructure–property relationships. During the past decade, considerable progress has been achieved in realizing stable HOFs with permanent porosities by focusing on the design of molecular building blocks in order to introduce rigidity, auxiliary [π···π] interactions, and interpenetration of their frameworks to sustain the extended networks. The applications of HOFs are far-reaching, spanning catalysis, energy, and biomedical products as well as the storage and separation of fine chemicals. In this paper, we, first of all, provide an overview of the chronological development of HOFs, starting from the seminal work by Marsh and Duchamp in 1969 on the crystal superstructure of the hydrogen-bonded networks of trimesic acid. We identify the development of novel hydrogen-bonding motifs such as diaminotriazine (DTA), the introduction of the concept of molecular tectonics, and the establishment of permanent porosity in HOFs as being some of the milestones, which incentivized the current burgeoning research endeavors on developing HOFs as multifunctional materials. This Account is focused primarily on surveying the strategies for constructing porous 3D HOFs based on organic building blocks with peripheral carboxyl groups. These strategies are presented in the following categories: (1) the polycatenation of 2D networks by trigonal building blocks to form global 3D frameworks, (2) the utilization of building blocks with 3D geometries—tetrahedral and trigonal prismatic—that are predisposed to form 3D networks, and (3) the docking by shape-fitting of geometrically labile building blocks. We emphasize how the molecular geometry of the building blocks plays an important role in modulating the superstructures of extended frameworks so as to address specific applications. Recognizing that the in silico design of HOFs is the ultimate goal of researchers in this field, we also discuss the recent advances in superstructure prediction that lead to the formation of porous supramolecular crystals and assess the complications in implementing computational methods for HOFs with complex superstructures. We hope this Account will inspire the development of new supramolecular designs and creative approaches to crystal engineering that aid and abet the assembly of multifunctional HOFs with customizable properties.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Sol-gel processing of a covalent organic framework for the generation of hierarchically porous monolithic adsorbents

Covalent organic frameworks (COFs) have emerged as a versatile material platform for such applications as chemical separations, chemical reaction engineering, and energy storage. Their inherently low mechanical stability, however, frequently renders existing methods of pelletization ineffective, contributing to pore collapse, pore blockage, or insufficient densification of crystallites. Here, we present a process for the shaping and densifying of COFs into robust centimeter-scale porous monoliths without the need for templates, additives, or binders. This process minimizes mechanical damage from shear-induced plastic deformation and further provides a network of interparticle mesopores that we exploit in accessing analyte capacities above those achievable from the intrinsic COF structure. Using a lattice-gas model, we accurately capture the monolithic structure across the mesoporous range and tie pore architecture to performance in both gas-storage and -separation applications. Collectively, these results represent a substantial step in the practical applicability of COFs and other mechanically weak porous materials.

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

Transport of polymer-coated metal–organic framework nanoparticles in porous media

Abstract Injecting fluids into deep underground geologic structures is a critical component to development of long-term strategies for managing greenhouse gas emissions and facilitating energy extraction operations. Recently, we reported that metal–organic frameworks are low-frequency, absorptive-acoustic metamaterial that may be injected into the subsurface to enhance geophysical monitoring tools used to track fluids and map complex structures. A key requirement for this nanotechnology deployment is transportability through porous geologic media without being retained by mineral-fluid interfaces. We used flow-through column studies to estimate transport and retention properties of five different polymer-coated MIL-101(Cr) nanoparticles (NP) in siliceous porous media. When negatively charged polystyrene sulfonate coated nanoparticles (NP-PSS-70K) were transported in 1 M NaCl, only about 8.4% of nanoparticles were retained in the column. Nanoparticles coated with polyethylenimine (NP-PD1) exhibited significant retention (> 50%), emphasizing the importance of complex nanoparticle-fluid-rock interactions for successful use of nanofluid technologies in the subsurface. Nanoparticle transport experiments revealed that nanoparticle surface characteristics play a critical role in nanoparticle colloidal stability and as well the transport.

58 GEOSCIENCES↗
DOE OSTI2024

Optimizing iodine adsorption in functionalized metal-organic frameworks via an unprecedented positional isomerism strategy

Porous metal–organic frameworks (MOFs) have emerged as highly promising adsorbents for capturing radioiodine, a predominant fission product released during nuclear fuel reprocessing. However, systematic investigations into the correlation between MOF structure and iodine uptake capacity remain scarce. Here, we present a novel approach to enhance the iodine adsorption capacity of MOFs by optimizing linker functionalization. Using ligand-functionalized thorium-based MOFs as a structural platform, we demonstrate that ortho-amino-substitution near the node of the dicarboxylate linker significantly increases iodine adsorption capacity compared to meta-amino-substitution, where the amino groups are directed away from the node. Specifically, ortho-substituted Th-UiO-68-3,3”-(NH 2 ) 2 exhibits higher iodine uptake capacities than the meta-substituted Th-UiO-68-2,2”-(NH 2 ) 2 via both vapor diffusion-based (2.042 vs. 1.087 g/g) and solution-based (0.841 vs. 0.784 g/g) processes. Notably, the I 2 vapor adsorption capacity (2.042 g/g) of Th-UiO-68-3,3”-(NH 2 ) 2 represents the second highest among all reported Th-MOFs. Pair distribution function (PDF) studies reveal that the superior iodine uptake performance of ortho-functionalized MOFs can be attributed to the reduced steric hindrance of the amino groups compared with the meta-substituted variants. Finally, this research highlights how positional isomerism and its subtle alterations can significantly influence host–guest interactions, extending beyond simple structural considerations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Fundamental studies of thermal and electrical transport in microporous metal-organic frameworks

In this work, we established porous metal-organic frameworks (MOFs) as designer conductors of electrons and ions relevant to fundamental research and technological applications. MOFs are porous, crystalline materials composed of organic linkers and inorganic nodes. While most MOFs are insulating with respect to ionic and electronic charge carriers, a number of exceptions have been reported in recent years. Electrically conductive MOFs are highly attractive for applications including electrical energy storage, chemiresistive sensing, and optoelectronics because of their high surface areas and tunable chemical properties. Ion-conducting MOFs are desirable for the synthetically tunable size, shape, and polarity of their pore environments, allowing for the tailored development of solid state electrolytes for metal-ion batteries. We developed systematic strategies for the design of MOFs that conduct ions and electrons. For each objective, we leveraged the versatile chemistry of these materials to obtain frameworks with targeted properties towards electronic or ionic charge carriers. We studied the factors that govern electrical transport in MOFs in order to gain fundamental knowledge of this emerging class of materials. We took several approaches to tackle this problem from multiple angles. Namely, we synthesized and characterized new frameworks, investigated post-synthetic modifications to enhance conductivity, and correlated theory and experiment to uncover new mechanistic findings. These results, which put forth new design principles for conductive MOFs, move the field toward one of the DOE Basic Energy Sciences Grand Challenges: to “design and perfect atom- and energy-efficient synthesis of revolutionary new forms of matter with tailored properties.” In addition to investigating the movement of electrons in MOFs, we also studied the movement of other charged species in MOFs, such as protons, lithium, and magnesium. Proton-conducting frameworks could be appealing materials for solid state electrolytes in fuel cells. In addition, they contain crystallographically defined proton-conducting channels, in contrast with state-of-the-art polymer membranes such as Nafion, which are amorphous. Controlling pore size and polarity in MOFs can thus shed light on proton and other ion transport mechanisms, ultimately enabling the design of more advanced electrolyte materials and potentially novel electrical energy storage materials.

36 MATERIALS SCIENCE↗
DOE OSTI2026

A Permanently Porous Chalcogen-Bonded Organic Framework

The nature of connectivity between constituent atomic or molecular building blocks is fundamental in shaping the properties and functionality of materials. The extrapolation of emergent interatomic interactions to enable functional materials has driven transformative technological advancements. However, the bonding interactions used in material design have been largely static since the emergence of dynamic covalent chemistry ~30 years ago. Here we demonstrate that non-covalent chalcogen bonding (Ch-bonding) is a distinct mode of interatomic connectivity for constructing functional materials by design. This is established by leveraging self-complementary assembly of 1,2,5-telluradiazole moieties to construct a honeycomb-type permanently porous Ch-bonded organic framework, assembled and stabilized solely through non-covalent Te...N contacts. Empirical and computational studies of electronic structure, structural healing and lattice dynamics highlight the pi-type electronic communication, controlled assembly and modulated lattice dynamics in Trip3Tez-I arising directly from the unique nature of the Te...N Ch-bonding that holds substantial implications for next generation crystalline semiconductors. In addition to introducing a distinct class of permanently porous frameworks, this work establishes Ch-bonding as a programmable molecular tool for constructing functional materials with distinct properties.

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

Sorption-based atmospheric water harvesting device

A water-harvesting system can operate with a material that can take up and release water with minimum energy requirements and powered by low-grade energy sources, such as sunlight, in order to potentially allow its deployment into households, especially those located in sunny regions. A water-harvesting method and system can include vapor adsorption using a porous metal-organic framework. In certain embodiments, the porous metal-organic framework can include metal-organic framework in ambient air with low relative humidity, typical of the levels found in most dry regions of the world.

42 ENGINEERING↗
DOE OSTI2020

Sorption-based atmospheric water harvesting device

A water-harvesting system can operate with a material that can take up and release water with minimum energy requirements and powered by low-grade energy sources, such as sunlight, in order to potentially allow its deployment into households, especially those located in sunny regions. A water-harvesting method and system can include vapor adsorption using a porous metal-organic framework. In certain embodiments, the porous metal-organic framework can include metal-organic framework in ambient air with low relative humidity, typical of the levels found in most dry regions of the world.

42 ENGINEERING↗
DOE OSTI2024

Tailorable Multi–Modular Pore–Space–Partitioned Vanadium Metal–Organic Frameworks for Gas Separation

Currently, few porous vanadium metal-organic frameworks (V-MOFs) are known and even fewer are obtainable as single crystals, resulting in limited information on their structures and properties. Here this work demonstrates remarkable promise of V-MOFs by presenting an extensible family of V-MOFs with tailorable pore geometry and properties. The synthesis leverages inter-modular synergy on a tri-modular pore-partitioned platform. New V-MOFs show a broad range of structural features and sorption properties suitable for gas storage and separation applications for C 2 H 2 /CO 2 , C 2 H 6 /C 2 H 4 , and C 3 H 8 /C 3 H 6 . The c/a ratio of the hexagonal cell, a measure of pore shape, is tunable from 0.612 to 1.258. Other tunable properties include pore size from 5.0 to 10.9 Å and surface area from 820 to 2964 m 2 g –1 . With C 2 H 2 /CO 2 selectivity from 3.3 to 11 and high uptake capacity for C 2 H 2 from 65.2 to 182 cm 3 g –1 (298K, 1 bar), an efficient separation is confirmed by breakthrough experiments. The near-record high uptake for C 2 H 6 (166.8 cm 3 g –1 ) contributes to the promise for C 2 H 6 -selective separation of C 2 H 6 /C 2 H 4 . The multi-module pore expansion enables transition from C 3 H 6 -selective to more desirable C 3 H 8 -selective separation with extraordinarily high C 3 H 8 uptake (254.9 cm 3 g –1 ) and high separation potential (1.25 mmol g –1 ) for C 3 H 8 /C 3 H 6 (50:50 v/v) mixture.

36 MATERIALS SCIENCE↗