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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Rational Design of A Chemical Bath Deposition Based Tin Oxide Electron Transport Layer for Perovskite Photovoltaics

Chemical bath deposition is widely used to deposit SnO x as an electron transport layer in perovskite solar cells (PSCs). The conventional recipe uses thioglycolic acid (TGA) to facilitate attachments of SnO x particles onto the substrate. However, nonvolatile TGA has been reported to harm the operational stability of PSCs. In this work, we introduced a volatile oxalic acid (OA) as an alternative to TGA. OA, a dicarboxylic acid, functions as a chemical linker for the nucleation and attachment of particles to the substrate in the chemical bath. Moreover, OA can be readily removed through thermal annealing followed by a mild H 2 O 2 treatment, as shown by FTIR measurements. Synergistically, the mild H 2 O 2 treatment selectively oxidizes the surface of the SnOx layer, minimizing nonradiative interface carrier recombination. EELS (electron-energy-loss-spectroscopy) confirms that the SnO x surface is dominated by Sn 4+ , while the bulk is a mixture of Sn 2+ and Sn 4+ . This rational design of a CBD SnO x layer leads to devices with T85~1,500h, a significant improvement over the TGA-based device with T80~250h. Our champion device reached a power conversion efficiency of 24.6%. This work offers a rationale for optimizing the complex parameter space of CBD SnO x to achieve efficient and stable PSCs.

14 SOLAR ENERGY↗
DOE OSTI2025

Cross-aldol condensation on missing linker sites of metal–organic framework UiO-66

Missing linkers induce coordinatively unsaturated Lewis acid-base pair sites in metal–organic frameworks such as UiO-66 (Zr). The Lewis acid-base pair is induced by replacing the benzene dicarboxylic acid linker with formic acid, which subsequently is thermally decomposed. The concentration of coordinatively unsaturated Zr 4+ cations was titrated with acetone. In parallel to their concentration, the catalytic activity increased while the selectivity for aldol condensation between furfural and acetone remained constant. The missing linkers generate a complex ensemble consisting of an (at least partly) accessible Zr 4+ cation surrounded by oxygen, catalyzing the cross-aldol condensation. As a result, density functional theory calculations, matching the experimental findings provide a more detailed understanding of the elementary steps during the condensation reaction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Transcriptomic and metabolomic analysis of recalcitrant phosphorus solubilization mechanisms in Trametes gibbosa

Introduction Phosphorus (P) is a crucial growth-limiting nutrient in soil, much of which remains challenging for plants to absorb and use. Unlike chemical phosphate fertilizers, phosphate-solubilizing microorganisms (PSMs) offer a means to address available phosphorus deficiency without causing environmental harm. PSMs possess multiple mechanisms for phosphorus solubilization. Although the phosphorus-solubilizing mechanisms of phosphate-solubilizing bacteria (PSB) have been well characterized, the mechanisms utilized by phosphate-solubilizing fungi (PSF) remain largely unexplored. Methods This study isolated a PSF strain, Trametes gibbosa T-41, from soil and evaluated its phosphorus solubilizing capacity with organic (calcium phytin; Phytin-P) and inorganic (tricalcium phosphate; Ca-P) phosphorus sources. The phosphorus solubilization, enzyme activity, and organic acid production of T-41 were measured. And the P-solubilizing mechanism conducted by transcriptomic and metabolomic analyses. Results and discussion T-41 exhibited varying phosphorus solubilizing capacity when grown with organic (calcium phytin; Phytin-P) and inorganic (tricalcium phosphate; Ca-P) phosphorus sources (109.80 ± 8.9 mg/L vs. 57.5 ± 7.9 mg/L, p < 0.05). Compared with the Ca-P treatment, T-41 demonstrated a stronger alkaline phosphatase (ALP) production capacity under Phytin-P treatment (34.5 ± 1.2 μmol/L/h vs. 19.8 ± 0.8 μmol/L/h, p < 0.05). Meanwhile, the production of oxalic acid, maleic acid, and succinic acid was higher under Phytin-P treatment ( p < 0.05). Transcriptomic and metabolomic analysis revealed that different phosphorus sources altered metabolic pathways such as galactose metabolism, glyoxylate and dicarboxylic acid metabolism, and ascorbate and aldolate metabolism. Key metabolites like myo-inositol, 2-oxoglutarate, and pyruvate were found to impact the performance of T. gibbosa T-41 differently under the two P sources. Notably, synthesis in Ca-P vs. Pytin-P, T-41 upregulated genes involved in myo-inositol synthesis, potentially enhancing its P-solubilizing ability. These results provide new insights into the molecular mechanisms of PSF at the transcriptomic and metabolomic levels, laying a theoretical foundation for the broader application of PSF as bio-phosphorus fertilizers in the future.

Chen, Yulan↗
DOE OSTI2025

Biotransformation of Phenolics in Spent Liquor from Aqueous Ammonia Pretreatment

Spent liquors of biomass pretreatment provide a source for renewable chemical production. These liquors require treatment before being discharged; otherwise, they negatively impact the environment. Herein, spent liquors from aqueous ammonia pretreatment of poplar wood are characterized for phenolic content via liquid chromatography–mass spectrometry and nuclear magnetic resonance spectroscopy. The main phenolics are phenol, p-hydroxybenzamide (pHBAm), and p-hydroxybenzoic acid (pHBA), of which pHBAm and pHBA are produced from the ester-linked p-hydroxybenzoates in poplar wood. Phenol is produced from pHBA via decarboxylation. The potential biotransformation of the extracted phenolics into 2-pyrone-4,6-dicarboxylic acid (PDC) is assessed using an engineered strain of Novosphingobium aromaticivorans DSM12444 (PDC strain). Biotransformation of pHBAm to PDC is shown to be possible in the presence of pHBA, but not when pHBAm is the sole phenolic substrate, this is the first reported observation of N. aromaticivorans producing PDC from an aromatic amide. The phenol present is not transformed to PDC and does not inhibit PDC production. This study demonstrates that the phenolic amide in spent liquor from ammonia pretreatment can be valorized via biotransformation using N. aromaticivorans, which adds to the growing versatility of N. aromaticivorans as a microbial chassis for converting plant-derived compounds to useful products.

biomass↗
DOE OSTI2022

Biological funneling of phenolics from transgenic plants engineered to express the bacterial 3-dehydroshikimate dehydratase (qsuB) gene

The economic and environmental sustainability of lignocellulosic biomass biorefineries is predicated on generating biofuels and bioproducts from cell-wall polysaccharide and lignin polymers. Historical efforts in plant genetic engineering have focused on the development of strategies that facilitate biomass deconstruction, with more recently efforts including the synthesis of high-value chemicals in planta . One such genetic modification is the expression of the bacterial quinate and shikimate utilization B ( qsuB ) gene that increases the accumulation of protocatechuic acid in lignocellulosic biomass. Herein, we evaluated the effectiveness of an alkaline pretreatment process to extract phenolics directly from wild-type and QsuB-transgenic lines of Arabidopsis, poplar, and sorghum, and then upgrade them to the polyester precursor 2-pyrone-4,6-dicarboxylic acid (PDC) with an engineered strain of Novosphingobium aromaticivorans . Protocatechuic acid extracted from all QsuB transgenic lines was found to be mostly in the glycosylated form. Glycosylated protocatechuic acid and other plant-derived phenolics were effectively metabolized by N. aromaticivorans, and PDC production was greatest using extracts from an Arabidopsis QsuB transgenic line (∼5% w/w), followed by QsuB sorghum (∼1.1% w/w), and QsuB poplar (∼0.4% w/w) lines. The comparison of PDC production from wild-type and QsuB transgenic lines of Arabidopsis, poplar, and sorghum demonstrates the utility of a mild alkaline pretreatment to liberate phenolics from plant biomass that are either naturally present or that accumulate as a consequence of genetic engineering strategies. All QsuB transgenic lines outperformed their wild-type counterparts with respect to observed PDC yields. In addition, microbial funneling to PDC was effective even when most of the protocatechuic acid extracted was in glycosylated form, clearly demonstrating that this bacterium can metabolize these aromatic conjugates. These findings illustrate the benefits of combining plant and microbial engineering for bioproduct formation from phenolics in lignocellulosic biorefineries.

Umana, German E.↗
DOE OSTI2022

Carboxylic acid ligand substituent impacts hydrosilylation activity of platinum single atom catalysts on ceria

Current industrially employed hydrosilylation catalysts rely on homogeneous platinum catalysts which are not recovered after the reaction. To eliminate this issue, our group has been working to optimize recyclability of heterogeneous platinum single atom catalysts (SACs) on ceria via 1,10-phenanthroline-5,6-dione ligands (PDO), which incorporates mono (PDO-C) and dicarboxylic acid (PDO-C2) groups in the 2- and 9-position of PDO ligand to increase metal–surface interaction. DRIFTS results confirm carboxylic acid coordination to the terminal hydroxy groups of the ceria surface. New catalyst synthesis conditions wherein PDO was combined with the metal prior to exposure to the surface allow control of Pt oxidation state on the surface. Here, the highest metal loading was observed for PDO and PDO-C, correlating with improved catalytic recyclability compared to the PDO-C2 ligand. It is proposed that the location of the carboxylic acid groups and the steric effects can explain the lower activity and metal loading for PDO-C2 ligands. Post-reaction XPS and DRIFTS spectra show the appearance of new Si and O species on the catalyst during the hydrosilylation reaction, indicating the silane reagent is depositing on the surface. The silane coverage and leaching of catalyst from the surface is the cause for the reduced catalytic activity.

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

Bifunctional Metal‐Organic Nanoballs Featuring Lewis Acidic and Basic Sites as a New Platform for One‐Pot Tandem Catalysis

Abstract The design and synthesis of polyhedra using coordination‐driven self‐assembly has been an intriguing research area for synthetic chemists. Metal‐organic polyhedra are a class of intricate molecular architectures that have garnered significant attention in the literature due to their diverse structures and potential applications. Hereby, we reportCu‐MOP, a bifunctional metal‐organic cuboctahedra built using 2,6‐dimethylpyridine‐3,5‐dicarboxylic acid and copper acetate at room temperature. The presence of both Lewis basic pyridine groups and Lewis acidic copper sites imparts catalytic activity to Cu‐MOP for the tandem one‐pot deacetalization‐Knoevenagel/Henry reactions. The effect of solvent system and time duration on the yields of the reactions was studied, and the results illustrate the promising potential of these metal‐organic cuboctahedra, also known as nanoballs for applications in catalysis.

Chemistry↗
DOE OSTI2026

Biocatalytic Carboxylic Acid Reduction and Transamination in Cell‐Free Lysates at High Substrate Loading

Chemoselective reduction of stable carboxylic acids to reactive aldehydes is of interest across many industries. While carboxylic acid reductases (CARs) are promising biocatalysts for this chemistry, poor chemoselectivity and low yield are commonly obtained when using less expensive crude lysate preparations and prerequisite ATP and NADPH regeneration systems. Here, in this work, we developed a highly chemoselective multienzyme cascade featuring a CAR and an ω-transaminase (TA) in crude lysate format, with conversion of the dicarboxylic acid terephthalic acid (TPA) into the diamine para -xylylenediamine (pXDA) as the model chemistry. We improved chemoselectivity for pXDA using engineered aldehyde-stabilizing Escherichia coli strains, though desired product yields remained modest. We next found that CAR activity was limited at high substrate loadings and overcame this bottleneck by modulating the ratio of polyphosphate (polyP 6 ) to Mg 2+ , enabling volumetric scaling and increased substrate loading up to 50 mM TPA. We then showcased the portability of this platform across substrates, resulting in the synthesis of four other high-value amines from carboxylate precursors. The combination of high carboxyl group turnover, up to 93.5 mM under the tested conditions, and the simplicity of crude enzyme preparation is a promising platform for sustainable functional group interconversion.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2026

Torsional Flexibility Tuning of Hexa-Carboxylate Ligands to Unlock Distinct Topological Access to Zirconium Metal–Organic Frameworks

Zirconium-based metal–organic frameworks (Zr-MOFs) exhibit remarkable structural diversity and functionality. However, uncovering new topological types within this family remains a considerable challenge today. Herein, we report two new hexa-topic ligands designed through the introduction of torsional flexibility, which enable the construction of two Zr-MOFs featuring rare network topologies. The (4,4′,4″,4‴,4‴′,4‴′′-((2-carboxybenzene-1,3,5-triyl)tris(9H-carbazole-9,3,6-triyl))hexabenzoic acid ligand (BTCH)) was obtained by replacing the rigid triptycene core in the H6PET-1 ligand (4,4′,4″,4‴,4‴′,4‴′′-(9,10-dihydro-9,10-[1,2]benzenoanthracene-2,3,6,7,14,15-hexayl)hexabenzoic acid) with a benzene-tricarbazole unit. Owing to its torsionally flexible core that allows rotational freedom to the arms, this ligand directs the construction of NU-2620 (NU represents Northwestern University), a Zr-MOF with 8-connected Zr6 clusters and the rare nuh topology. Further flexibilization of the carbazole units to benzene rings yielded the even more torsionally flexible 5′,5‴-bis(4-carboxyphenyl)-5″-(4,4″-dicarboxy-[1,1′:3′,1″-terphenyl]-5′-yl)-[1,1′:3′,1″:3″,1‴:3‴,1‴′-quinquephenyl]-4,4‴′-dicarboxylic acid ligand (CCTT), which forms NU-2630 featuring 6-connected clusters and the pcu topology. Both frameworks exhibit good chemical stability, prompting evaluation of their performance in CO2 photoreduction catalysis. Under low-concentration CO2 conditions, NU-2620 displays markedly higher catalytic activity than its benzene-based analogue, NU-2630, thanks to the abundance of photoactive carbazole units within its structure. These results demonstrate that introducing torsional flexibility in high-connected linkers can unlock access to new topologies and accelerates the reticular expansion of Zr-MOFs.

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

Vacancy Mediated Electrooxidation of 5‐Hydroxymethyl Furfuryl Using Defect Engineered Layered Double Hydroxide Electrocatalysts

Abstract Electrochemical biomass oxidation coupled with hydrogen evolution offers a promising route to generate value‐added chemicals and clean energy. The complex adsorption behavior of 5‐hydroxymethyl furfural (HMF) and hydroxyl ions (OH − ) on the electrocatalyst surface during HMF electrooxidation reaction (HMFOR) necessitates an in‐depth understanding of active sites available for adsorption. Herein, oxygen vacancy (V O ) defects are introduced in NiFe layered double hydroxide (LDH) using Ce dopants to manipulate electronic structure. Synchrotron‐based HE‐XRD and XAS indicate negligible V O in La‐doped NiFe while Ce doping leads to V O defects due to flexible Ce redox (Ce 3+ ↔ Ce 4+ ). The V O ‐rich Ce‐NiFe exhibits higher Faradic efficiency of ≈90% to produce 2,5‐furan dicarboxylic acid (FDCA), far greater than ≈60% for NiFe V O in Ce‐NiFe act as alternative active sites for OH − adsorption, hence reducing adsorption competition for the same metal sites. DFT calculation results corroborate experimental findings by showcasing that the presence of V O in Ce‐NiFe manipulates the adsorption energies and facilitates the chemical adsorption OH − in V O to improve HMFOR. In situ HE‐XRD derived pair distribution function coupled to RMC simulations confirm OH − trapping in V O and HMF adsorption on metal centers as evident by interlayer distance evolution. Taken together, this work showcases routes for dual‐site electrocatalyst design for improved biomass electrooxidation.

Chemistry↗
DOE OSTI2020

Dissipative Assembly of Macrocycles Comprising Multiple Transient Bonds

Abstract Dissipative assembly has great potential for the creation of new adaptive chemical systems. However, while molecular assembly at equilibrium is routinely used to prepare complex architectures from polyfunctional monomers, species formed out of equilibrium have, to this point, been structurally very simple. In most examples the fuel simply effects the formation of a single short‐lived covalent bond. Herein, we show that chemical fuels can assemble bifunctional components into macrocycles containing multiple transient bonds. Specifically, dicarboxylic acids give aqueous dianhydride macrocycles on treatment with a carbodiimide. The macrocycles are assembled efficiently as a consequence of both fuel‐dependent and fuel‐independent mechanisms; they undergo slower decomposition, building up as the fuel recycles the components, and are a favored product of the dynamic exchange of the anhydride bonds. These results create new possibilities for generating structurally sophisticated out‐of‐equilibrium species.

Hossain, Mohammad Mosharraf↗
DOE OSTI2023

Pore Aperture Control Toward Size‐Exclusion‐Based Hydrocarbon Separations

Abstract Metal–organic frameworks (MOFs) have been proposed as a promising material for non‐thermal chemical separations owing to their high structural diversity and tunability. Here, we report the synthesis of a zinc‐based MOF containing a three‐dimensional (3D) linker, bicyclo[2.2.2]octane‐1,4‐dicarboxylic acid, with high thermal stability towards the separation of hexane isomers. The incorporation of the 3D linker enhances the structural stability and provides well‐defined pore apertures/channels with sub‐Ångstrom precision. This precision allowed for the separation of similarly sized hexane isomers based on subtle differences in their kinetic diameters. Multi‐component liquid phase batch experiments confirmed the separation of hexanes mixture into linear, monobranched, and dibranched isomers. This work represents a significant milestone in the construction of stable Zn‐based MOFs and the incorporation of 3D linkers as a potential solution to challenging separations.

Lal, Bhajan↗
DOE OSTI2023

Pore Aperture Control Toward Size‐Exclusion‐Based Hydrocarbon Separations

Metal–organic frameworks (MOFs) have been proposed as a promising material for non-thermal chemical separations owing to their high structural diversity and tunability. Here, we report the synthesis of a zinc-based MOF containing a three-dimensional (3D) linker, bicyclo[2.2.2]octane-1,4-dicarboxylic acid, with high thermal stability towards the separation of hexane isomers. The incorporation of the 3D linker enhances the structural stability and provides well-defined pore apertures/channels with sub-Ångstrom precision. This precision allowed for the separation of similarly sized hexane isomers based on subtle differences in their kinetic diameters. Multi-component liquid phase batch experiments confirmed the separation of hexanes mixture into linear, monobranched, and dibranched isomers. This work represents a significant milestone in the construction of stable Zn-based MOFs and the incorporation of 3D linkers as a potential solution to challenging separations.

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

Transient Covalent Polymers through Carbodiimide‐Driven Assembly

Biochemical systems make use of out-of-equilibrium polymers generated under kinetic control. Inspired by these systems, many abiotic supramolecular polymers driven by chemical fuel reactions have been reported. Conversely, polymers based on transient covalent bonds have received little attention, even though they have the potential to complement supramolecular systems by generating transient structures based on stronger bonds and by offering a straightforward tuning of reaction kinetics. In this study, we show that simple aqueous dicarboxylic acids give poly(anhydrides) when treated with the carbodiimide EDC. Transient covalent polymers with molecular weights exceeding 15,000 are generated which then decompose over the course of hours to weeks. Disassembly kinetics can be controlled using simple substituent effects in the monomer design. The impact of solvent polarity, carbodiimide concentration, temperature, pyridine concentration, and monomer concentration on polymer properties and lifetimes has been investigated. The results reveal substantial control over polymer assembly and disassembly kinetics, highlighting the potential for fine-tuned kinetic control in nonequilibrium polymerization systems.

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

Temporally Stable Supramolecular Polymeric Salts Enabling High-Performance 3D All-Aromatic Polyimide Lattices

Vat photopolymerization (VP) Additive Manufacturing (AM), in which UV light is selectively applied to cure photo-active polymers into complex geometries with micron-scale resolution, has a limited selection of aliphatic thermoset materials that exhibit relatively poor thermal performance. Ring-opening dianhydrides with acrylate-containing nucleophiles yielded diacrylate ester-dicarboxylic acids that enabled photo-active polyimide (PI) precursors, termed polysalts, upon neutralization with an aromatic diamine in solution. In situ FTIR spectroscopy coupled with a solution and photo-rheological measurements revealed a previously unknown time-dependent instability of 4,4'-oxydianiline (ODA) polysalts due to an aza-Michael addition. Replacement of the electron-donating ether-containing diamine with an electron withdrawing sulfone-containing monomer, e.g., 4,4'-diaminodiphenyl sulfone (DDS), prohibited the aza-Michael addition of the aromatic amine to the activated acrylate double bond. Novel DDS polysalt photocurable solutions are similarly analyzed and validated long-term stability, which enabled reproducible printing of polyimide organogel intermediates. Subsequent VP AM afforded 3-dimensional (3D) structures of intricate complexity and excellent surface finish, as demonstrated with scanning electron microscopy. In addition, the novel PMDA-HEA/DDS solution enabled the production of the first beam latticed architecture comprised of all-aromatic polyimide. Finally, the versatility of a polysalt platform for multi-material printing is further demonstrated by printing parts with alternating polysalt compositions.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Covalent Triazine-Based Frameworks with Ru-tda Based Catalyst Anchored via Coordination Bond for Photoinduced Water Oxidation

Light-induced water splitting (hν-WS) for the production of hydrogen as a solar fuel is considered a promising sustainable strategy for the replacement of fossil fuels. An efficient system for hν-WS involves a photoactive material that, upon shining light, is capable of separating and transferring charges to catalysts for the hydrogen and oxygen evolution processes. Covalent triazine-based frameworks (CTFs) represent an interesting class of 2D organic light-absorbing materials that have recently emerged thanks to their tunable structural, optical and morphological properties. Typically, catalysts (Cat) are metallic nanoparticles generated in situ after photoelectroreduction of metal precursors or directly drop-casted on top of the CTF material to generate Cat-CTF assemblies. Here, in this work, the synthesis, characterization and photocatalytic performance of a novel hybrid material, Ru-CTF, is reported, based on a CTF structure featuring dangling pyridyl groups that allow the Ru-tda (tda is [2,2':6',2'“-terpyridine]-6,6'”-dicarboxylic acid) water oxidation catalyst (WOC) unit to coordinate via covalent bond. The Ru-CTF molecular hybrid material can carry out the light-induced water oxidation reaction efficiently at neutral pH, reaching values of maximum TOF of 17 h -1 and TONs in the range of 220 using sodium persulfate as a sacrificial electron acceptor.

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

Establishing substitution rules of functional groups for high-capacity organic anode materials in Na-ion batteries

Tailoring molecular structures of organic electrode materials (OEMs) can enhance their performance in Na-ion batteries, however, the substitution rules and the consequent effect on the specific capacity and working potential remain elusive. Herein, by examining three sodium carboxylates with selective N substitution or extended conjugation structure, we exploited the correlation between structure and performance to establish substitution rules for high-capacity OEMs. Our results show that substitution position and types of functional groups are essential to create active centers for uptake/removal of Na+ and thermodynamically stabilize organic structures. Furthermore, rational host design and electrolytes modulation were performed to extend the cycle life to 500 cycles. A full cell based on the optimal 2,2’-bipyridine-4,4’-dicarboxylic acid disodium salt anode and the polyaniline cathode is demonstrated to confirm the feasibility of achieving all-organic batteries. Lastly, this work provides a valuable guideline for the design principle of high-capacity and stable OEMs for sustainable energy storage.

25 ENERGY STORAGE↗