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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

A one-pot synthesis of high-density biofuels through bifunctional mesoporous zeolite-encapsulated Pd catalysts

Developing a powerful bifunctional catalyst for tandem reactions is essential to the future carbon neutrality by reducing the energy consumption in chemical industries. Herein, mesoporous zeolite-encapsulated palladium (Pd) nanoparticles (Pd@meso-ZSM-5) synthesized via emulsification-demulsification followed by a dry-gel transformation method were demonstrated to have a remarkable catalytic performance for a one-pot multiple tandem reaction of cyclic ketones (cyclopentanone, cyclohexanone) to bicyclic alkanes (bicyclopentane, bicyclohexane). Compared with supported catalysts (Pd/meso-ZSM-5) and microporous zeolite-encapsulated catalysts (Pd@ZSM-5) with a primary product of monocyclic alkane (cyclopentane, cyclohexane), Pd@meso-ZSM-5 shows much higher catalytic efficiency for the bicyclic alkanes synthesis, which was previously unattainable in the conventional two-step synthesis route. Controlled experiments and detailed characterizations show that mesoporosity provides sufficient space for the generation and diffusion of large molecular intermediates, and the intimate acid-Pd interface promotes the conversion of intermediates. As a result, this work proposes a design strategy for a mesoporous zeolite-encapsulated metal catalyst, which efficiently provides cooperative acid-hydrogenation catalysis.

09 BIOMASS FUELS↗
DOE OSTI2022

Encapsulation of hygroscopic liquids via polymer precipitation in non-aqueous emulsions

Here, encapsulation of ionic liquids (ILs) and phase change materials (PCMs) can overcome limitations associated with bulk materials, e.g., slow mass transfer rates, high viscosities, or susceptibility to external environment. Single step soft-templated encapsulation methods commonly use interfacial polymerization for shell formation, with a multifunctional monomer in the continuous phase and another in the discontinuous phase, and thus do not give pristine core material. We posit that polymer precipitation onto emulsion droplets in non-aqueous emulsions could produce a robust shell without contamination of the core, ideal for the encapsulation of water-sensitive or water-miscible materials. Solutions of commodity polymers were added to the continuous phase of non-aqueous Pickering emulsions stabilized by alkylated graphene oxide (GO) nanosheets such that the change in solubility of the polymer led to formation of robust shells and the production of capsules that could be isolated. We demonstrate that a polymer precipitation approach can produce capsules with pristine core of the IL 1-ethyl-3-methylimidazolium hexafluorophosphate [Emim][PF 6 ] or the salt hydrate PCM magnesium nitrate hexahydrate (MNH) and shell of nanosheets and polystyrene, poly(methyl methacrylate), or polyethylene. The capsules are approximately 80 wt% [Emim][PF 6 ] or >90 wt% MNH, and the core can undergo multiple cycles of solidification and melting without leakage or destruction. This novel, single-step methodology provides a distinct advantage to access capsules with pristine core composition and is amenable to different core and shell, paving the way for tailoring capsule composition for desired applications.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Impulse-driven release of gas-encapsulated drops

Gas-encapsulated drops, much like antibubbles, are drops enclosed in a bubble within a liquid. They show potential as payload carriers in fluid transport and mixing techniques where sound waves can be leveraged to induce the collapse of the gas core and the subsequent release of the drop. Here, the interaction of millimetre-sized gas-encapsulated drops with impulsive laser-induced shock waves is investigated to gain fundamental insights into the release process. Experimental synchrotron X-ray phase contrast imaging, which allows the drop dynamics to be visualised inside the encapsulating bubble, is complemented by numerical simulations to study the intricate physics at play. Three drop dynamical release regimes are discovered, namely the drop impact , partial deposition and jet impact regimes. The regime type is mainly dependent on the shape of the bubble interface impacting the drop and the associated Weber and Reynolds numbers. The drop dynamics of the drop impact and partial deposition regimes show similarities with the canonical configuration of drops impacting flat liquid surfaces, whereas the jet impact regime resembles binary drop collisions, which allows existing scaling laws to be applied to describe the underlying processes. The release of the drop is investigated numerically. The time evolution of the drop dissemination within the surrounding liquid discloses enhanced mixing for dynamics involving high Weber and Reynolds numbers such as the drop impact and jet impact regimes.

42 ENGINEERING↗
DOE OSTI2021

Tuning the Conductivity of Hexa-Zirconium(IV) Metal–Organic Frameworks by Encapsulating Heterofullerenes

Electrical conductivity in metal–organic frameworks (MOFs) has a great potential for energy storage applications and electrocatalysis. Zirconium-based MOFs such as NU-901 and NU-1000 have a low electrical conductivity due to the redox innocence of Zr–oxo bonds. Recently, it has been shown that the electrical conductivity of NU-901 can be increased by 11 orders of magnitude by physically encapsulating fullerene (C 60 ) in its diamond pore. This effect is due to the host–guest interaction between the electron-rich 1,3,6,8-tetrakis(p-benzoate)pyrene (TBAPy 4– ) organic linkers of NU-901 (host) and the electron-poor fullerene (guest). Herein, we used density functional theory to study heterofullerene (C 59 X; X = B, Al, Ga, In, Si, Ge, and Sn) encapsulation in NU-901. Furthermore, our study suggests that encapsulated heterofullerenes enhance the electrical conductivity of the NU-901 MOF even further than C 60 .

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

In Vitro Encapsulation of Functionally Active Abiotic Photosensitizers Inside a Bacterial Microcompartment Shell

Bacterial microcompartments (BMCs) are self-assembling, selectively permeable protein shells that encapsulate enzymes to enhance catalytic efficiency of segments of metabolic pathways through means of confinement. The modular nature of BMC shells' structure and assembly enables programming of shell permeability and underscores their promise in biotechnology engineering efforts for applications in industry, medicine, and clean energy. Realizing this potential requires methods for encapsulation of abiotic molecules, which have been developed here for the first time. We report in vitro cargo loading of BMC shells with ruthenium photosensitizers (RuPS) by two approaches-one involving site-specific covalent labeling and the other driven by diffusion, requiring no specific interactions between cargo molecules and shell proteins. The highly stable shells retain encapsulated cargo over 1 week without egress and preserve RuPS photophysical activity. Finally, this study is an important foundation for further work that will converge biological BMC architecture with synthetic chemistry to facilitate biohybrid photocatalysis.

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

Quantifying the Influence of Defects on Selectivity of Electrodes Encapsulated by Nanoscopic Silicon Oxide Overlayers

Encapsulation of electrocatalysts and photocatalysts with semipermeable nanoscopic oxide overlayers that exhibit selective transport properties is an attractive approach to achieve high redox selectivity. However, defects within the overlayers-such as pinholes, cracks, or particle inclusions-may facilitate local high rates of parasitic reactions by creating pathways for facile transport of undesired reactants to exposed active sites. Scanning electrochemical microscopy (SECM) is an attractive method to determine the influence of defects on macroscopic performance metrics thanks to its ability to measure the relative rates of competing electrochemical reactions with high spatial resolution over the electrode. Here, we report the use of SECM to determine the influence of overlayer defects on the selectivity of silicon oxide (SiOx) encapsulated platinum thin-film electrocatalysts operated under conditions where two competing reactions-the hydrogen evolution and Fe(III) reduction reactions-can occur. After an SECM methodology is described to determine spatially resolved selectivity, representative selectivity maps are correlated with the location of defects that are characterized by optical, electron, and atomic force microscopies. This analysis reveals that certain types of defects in the oxide overlayer are responsible for ∼60-90% of the partial current density toward the undesired Fe(III) reduction reaction. By correcting for defect contributions to Fe(III) reduction rates, true Fe(III) permeability values for the SiOxoverlayers were determined to be over an order of magnitude lower than permeabilities determined from analyses that ignore the presence of defects. Lastly, different types of defects were studied revealing that defect morphology can have varying influence on both redox selectivity and calculated permeability. This work highlights the need for spatially resolved measurements to evaluate the performance of oxide-encapsulated catalysts and understand their performance limits.

25 ENERGY STORAGE↗
DOE OSTI2023

Encapsulating Semiconductor Quantum Dots in Supramolecular Cages Enables Ultrafast Guest–Host Electron and Vibrational Energy Transfer

In the field of supramolecular chemistry, host- guest systems have been extensively explored to encapsulate a wide range of substrates, owing to emerging functionalities in nano-confined space that cannot be achieved in dilute solutions. However, host-guest chemistry is still limited to encapsulation of small guests. Herein, we construct a water-soluble metallo-supramolecular hexagonal prism with a large hydrophobic cavity by anchoring multiple polyethylene glycol chains onto the building blocks. Then, assembled prisms are able to encapsulate quantum dots (QDs) with diameters of less than 5.0 nm. Furthermore, we find that the supramolecular cage around each QD strongly modifies the photophysics of the QD by universally increasing the rates of QD relaxation processes via ultrafast electron and vibrational energy transfer. In conclusion, taken together, these efforts expand the scope of substrates in host-guest systems and provide a new approach to tune the optical properties of QDs.

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

Encapsulation Residual Stress and Ferrite Loss in Inductive Coil Assemblies

As inductive wireless charging reaches higher power levels, thermal management and mechanical durability become more critical. To address these concerns, past works have demonstrated the benefit of encapsulating coil assemblies in thermally conductive materials. However, due to the sensitivity of the MnZn ferrites commonly used in coil assemblies to mechanical stress, care must be taken to avoid creating large stresses in the ferrite that cause higher hysteresis loss. The stress formation in the encapsulant curing process is overviewed and modeled and an experiment is performed to demonstrate the effect in a small-scale coil assembly. Finally, the effect is shown in the reduced coil-coil efficiency of a first generation high power inductive power transfer prototype using a stiff epoxy compared to better performance in a second prototype using a softer thermally-conductive silicone encapsulant.

Foote, Andrew↗
DOE OSTI2019

Field-Aged Glass/Backsheet and Glass/Glass PV Modules: Encapsulant Degradation Comparison

Ethylene vinyl acetate (EVA) is the predominant encapsulant in crystalline-silicon photovoltaic (PV) modules; however, its degradation is a subject of major concern, which causes significant power loss under field conditions. This article presents a comparison of EVA degradation in field-aged PV modules with glass/backsheet (G/B) and glass/glass (G/G) architectures. Modulelevel characterization included UV fluorescence imaging and I-V measurements. Material analytical techniques, including colorimetry, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Raman spectroscopy, were performed to correlate the module performance parameters with EVA material properties. An intense EVA discoloration in G/G modules was observed, which was corroborated by higher module Isc and Pmax degradation rates compared with its counterpart G/B modules. Higher power degradation was accompanied by a significant increase in EVA crosslinking, vinyl acetate content, yellowness index, and presence of functional groups containing unsaturated moieties that are linked to degradation products of photothermal reaction, and a higher decrease in the degree of crystallinity. The absence of a polymeric backsheet in hermetically sealed G/G modules, which restricts photobleaching and enhances the entrapment of volatile acetic acid and other degradation by-products, plays a major role in causing higher EVA degradation in G/G modules. This article concludes that EVA might have been a good choice of an encapsulant for the G/B modules over the decades, but it may prove to be an inappropriate choice for the G/G modules because of potential degassing, corrosion, and/or discoloration issues. Ionomers or polyester-based encapsulants like polyolefins could be best suited for G/G modules as it appears to be a current trend in the industry.

14 SOLAR ENERGY↗
DOE OSTI2021

Cold Sintered Ceramics and Cements for Part Encapsulation

In this project, ceramic encapsulation materials were studied for high temperature (>~°500 C) applications where typical polymer encapsulants are unstable. A new low temperature (<~°200 C) method of processing ceramics, the cold sintering process was examined. Additionally, commercially available high temperature ceramic cements were investigated. In both cases, the mechanical strengths of available materials are less than desired (i.e., desired strengths similar to Si 3 N 4 ), limiting applicability. Composite designs to increase mechanical strength are suggested. Additionally, non-uniformities in stresses and densification while embedding alumina sheets in encapsulants via cold sintering using uni-axial pressing led to fracture of sheets, and an alternative iso-static based approach is recommended for future studies.

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

High Strength, Encapsulated, Commercially Useful Components and Particles Made from Coal Combustion Residuals

This project has developed and demonstrated two high-volume applications for Coal Combustion Residuals (CCR) with annual usage on the order of billions of pounds. The CCR is encapsulated in a recently developed water-impervious inorganic resin coating to reduce leaching of toxic elements from CCR by more than 80% as a first step. Target commercial applications demonstrated for the encapsulated CCR were as reinforcement for high-strength structural columns composed of CCR embedded in a ceramic matrix and as filler in high-volume plastics such as polypropylene. The encapsulated particles produced columns with properties superior to concrete, and a 30% to 50% improvement in stiffness over current fillers in plastics. CCR from bituminous and lignite coal was evaluated and shown to provide high performance, with the bituminous CCR producing the strongest columns and the lignite-based CCR provided the best performance as coated filler in polypropylene. The two-year project advanced both material systems from a Technology Readiness Level (TRL) of 2 to TRL 4.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2025

Developing the Science Basis for Understanding Polymer Encapsulant Degradation Mechanisms: DuraMAT 2.0 Final Project Report

Polymeric encapsulants are essential materials in photovoltaic modules, protecting sensitive electronics from the environment while providing mechanical integrity to the multilayered assembly. However, these polymeric materials are susceptible to degradation processes driven by the ingress of environmental species, ultraviolet radiation, thermal stresses, and mechanical loading. In this study, we employ a combined atomistic simulation and accelerated aging experimental approach to study the molecular-scale mechanisms of encapsulant degradation. Classical molecular dynamics simulations quantify the diffusion of environmental and degradation species through the polymer matrix, producing composition-specific diffusion coefficients. Reactive simulations characterize activation energy barriers and reaction rate constants for key chemical pathways. In parallel, thermal-desorption analyses coupled with mass spectrometry monitor the emergence and concentration profiles of degradation products under controlled stressor conditions. By integrating simulation and experiment, we establish quantitative correlations between polymer composition, species diffusivity, and chemical reactivity. We anticipate that these relations and quantitative values could serve as high-fidelity inputs to reaction-diffusion models, enabling physics-informed lifetime predictions and guiding the design of more durable encapsulant materials for solar energy applications.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Encapsulated sulfide glass solid electrolytes and solid-state laminate electrode assemblies

Nanofilm-encapsulated sulfide glass solid electrolyte structures and methods for making the encapsulated glass structures involve a lithium ion conducting sulfide glass sheet encapsulated on its opposing major surfaces by a continuous and conformal nanofilm made by atomic layer deposition (ALD). During manufacture, the reactive surfaces of the sulfide glass sheet are protected from deleterious reaction with ambient moisture, and the nanofilm can be configured to provide additional performance advantages, including enhanced mechanical strength and improved chemical resistance.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Encapsulated sulfide glass solid electrolytes and solid-state laminate electrode assemblies

Nanofilm-encapsulated sulfide glass solid electrolyte structures and methods for making the encapsulated glass structures involve a lithium ion conducting sulfide glass sheet encapsulated on its opposing major surfaces by a continuous and conformal nanofilm made by atomic layer deposition (ALD). During manufacture, the reactive surfaces of the sulfide glass sheet are protected from deleterious reaction with ambient moisture, and the nanofilm can be configured to provide additional performance advantages, including enhanced mechanical strength and improved chemical resistance.

Visco, Steven J.↗
DOE OSTI2021

Hybrid chip-on-board LED module with patterned encapsulation

Light modules and methods of forming light modules are disclosed. A light module includes a first plurality and a second plurality of light emitting elements configured to emit, respectively, a first light and a second light, and both arranged on a substrate. An encapsulation layer is disposed over the first and second plurality of the light emitting elements, and a wavelength converting element is dispersed in the encapsulation layer. A concentration of the wavelength converting element in the encapsulation layer varies, is larger over the first plurality of light emitting elements and is smaller over the second plurality of light emitting elements.

Soer, Wouter Anthon↗
DOE OSTI2022

Value Proposition of UV-Absorbers in PV Module Encapsulation

Various common crystalline silicon cell technologies were exposed to UVA radiation (1.24 Wm-2 nm-1 at 340 nm peak) on the front and back faces at 45 degrees Celsius for periods up to 3000 h, representing about 3 y of solar exposure in Phoenix, Arizona, USA. The resulting degradation of the open-circuit voltage and short-circuit current is presented. Of the various cell types examined, significant levels of degradation were seen in all cases. Less degradation was generally found after UV irradiation of cell fronts and older cell types, whereas a bifacial PERC type exposed on the rear showed about 25% degradation in short circuit current, attributable to lack of a diffused surface field. Selected cells were exposed to UV irradiation with the addition of long pass UV filters to replicate UV-absorbers in encapsulants. Modern cell designs are sensitive to UV-ID because of reduced or eliminated front and back surface field and increased dependence on high quality surface passivation. Single transformation of the independent variable (t, kW h/m^2) could be used to achieve a linear model of the data to extrapolate to 50 y. Solar Advisor Model (SAM) shows appropriate filtering of UV-irradiation can improve LCOE and net present value of plant. Some advanced cell types are seen to be UV-resistant (cell level solutions also exist). Solutions therefore exist on the cell, glass, and encapsulant level. Changes over time in each of these would also need to be considered (solarization, encapsulant browning...).

ENGINEERING,SOLAR ENERGY↗
DOE OSTI2022

Encapsulated sulfide glass solid electrolytes and solid-state laminate electrode assemblies

Nanofilm-encapsulated sulfide glass solid electrolyte structures and methods for making the encapsulated glass structures involve a lithium ion conducting sulfide glass sheet encapsulated on its opposing major surfaces by a continuous and conformal nanofilm made by atomic layer deposition (ALD). During manufacture, the reactive surfaces of the sulfide glass sheet are protected from deleterious reaction with ambient moisture, and the nanofilm can be configured to provide additional performance advantages, including enhanced mechanical strength and improved chemical resistance.

Visco, Steven J.↗
DOE OSTI2020

3D RNA nanocage for encapsulation and shielding of hydrophobic biomolecules to improve the in vivo biodistribution

Ribonucleic acid (RNA) nanotechnology platforms have the potential of harboring therapeutics for in vivo delivery in disease treatment. However, the nonspecific interaction between the harbored hydrophobic drugs and cells or other components before reaching the diseased site has been an obstacle in drug delivery. In this work, we report an encapsulation strategy to prevent such nonspecific hydrophobic interactions in vitro and in vivo based on a self-assembled three-dimensional (3D) RNA nanocage. By placing an RNA three-way junction (3WJ) in the cavity of the nanocage, the conjugated hydrophobic molecules were specifically positioned within the nanocage, preventing their exposure to the biological environment. The assembly of the nanocages was characterized by native polyacrylamide gel electrophoresis (PAGE), atomic force microscopy (AFM), and cryogenic electron microscopy (cryo-EM) imaging. The stealth effect of the nanocage for hydrophobic molecules in vitro was evaluated by gel electrophoresis, flow cytometry, and confocal microscopy. The in vivo sheathing effect of the nanocage for hydrophobic molecules was assessed by biodistribution profiling in mice. The RNA nanocages with hydrophobic biomolecules underwent faster clearance in liver and spleen in comparison to their counterparts. Therefore, this encapsulation strategy holds promise for in vivo delivery of hydrophobic drugs for disease treatment.

59 BASIC BIOLOGICAL SCIENCES↗