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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 1,387 records · Page 77
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Enhanced photocatalytic degradation of phenol over Ag3PO4-BiOCl1−xBrx composites

Highlights: • Ag{sub 3}PO{sub 4}-BiOCl{sub 1−x}Br{sub x} composites were successfully synthesized and characterized. • The band energy of composites can be tunable by solid-solution strategy. • Appropriate band-gap structure facilitates charge separation property and light absorption. - Abstract: In this paper, a series of Ag{sub 3}PO{sub 4}-BiOCl{sub 1−x}Br{sub x} composites with adjustable band gap has been fabricated by using a facile two-step synthetic method. The photocatalytic activity of Ag{sub 3}PO{sub 4}-BiOCl{sub 1−x}Br{sub x} was evaluated by photocatalytic decomposition of phenol aqueous solution under simulated solar light irradiation. The result shows that Ag{sub 3}PO{sub 4}-BiOCl{sub 0.75}Br{sub 0.25} (1:5) composite possesses the best photocatalytic activity among all the as-prepared samples. The photocatalytic activity of Ag{sub 3}PO{sub 4}-BiOCl can be enhanced mainly owing to the strong light absorption ability by loading Ag{sub 3}PO{sub 4} on the surface of BiOCl, while the photocatalytic activities of Ag{sub 3}PO{sub 4}-BiOCl{sub 1−x}Br{sub x} (x = 0.25, 0.5, 0.75 and 1) composites could be enhanced by restraining the recombination of photo-generated electron-hole pairs. The enhanced solar-light photocatalytic activities of Ag{sub 3}PO{sub 4}-BiOCl{sub 1−x}Br{sub x} composites could be ascribed to the adjustable energy band structure, which facilitates the separation of photoinduced carriers. In addition, superoxide radicals (O{sub 2}{sup −}), holes (h{sup +}) and OH are considered to dominate the photocatalytic degration process. Moreover, a possible mechanism of deep understanding on the base of experimental results was proposed.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Target preparation of multicomponent composites Au@CdS/g-C3N4 as efficient visible light photocatalysts with the assistance of biomolecules

Highlights: • Au@CdS/g-C{sub 3}N{sub 4} composites were prepared through a novel biomolecules assisted hydrothermal route. • Au@CdS core-shell structure is formed in composites. • The composites exhibit high visible light photocatalytic activity and stability. • The enhanced photocatalytic properties are ascribed to the efficient charges separation. - Abstract: In this work, we aimed to develop a novel method for the target preparation of multicomponent composites Au@CdS/g-C{sub 3}N{sub 4} towards high visible light photocatalytic activity with the assistance of L-cysteine biomolecules. Through the interaction of L-cysteine biomolecules with Au nanoparticles and g-C{sub 3}N{sub 4} bulks, CdS layer were in-situ precipitated on the surface of Au nanoparticles to form core-shell structure Au@CdS and Z-scheme structure Au@CdS-g-C{sub 3}N{sub 4} with good interface bonding in composites. By taking advantage of this feature, the highest reaction rate constant of 8%Au@CdS/g-C{sub 3}N{sub 4} for methyl orange dye and phenol degradation was 3.08- and 1.48-folds higher than pure g-C{sub 3}N{sub 4} bulks, which was ascribed to the strong interaction between different substances for efficient charges transferring and separation as evidenced by the studies of X-ray photoelectron spectroscopy, steady-state and transient photoluminescence spectroscopy. This work highlights the utilization of biomolecules for the target preparation of composites and its application on environmental remediation.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2020

PdAu/YSZ composite hydrogen separation membranes with enhanced stability in the presence of CO

The effects of gold composition on the tolerance of palladium-based composite membranes to CO exposure was studied under the presence of high CO concentrations. Membranes with PdAu compositions ranging up to 41% by mass were exposed to binary 50/50 H 2 /CO gas atmospheres and both hydrogen flux and purity were monitored over time. It was observed that the highest gold composition (41%) suffered no degradation in membrane performance in terms of permeate hydrogen purity and hydrogen permeation flux during the 48 h exposure. Furthermore, for lower gold compositions, X-ray diffraction patterns suggested that carbon entered the film and could be removed by exposure to a non-CO containing gas mixture over time. However, removal of the carbon adversely affected purity; interestingly, some of the purity decline could be reversed upon re-exposure to the CO gas mixture. It is hypothesized that carbon loading in the palladium films causes lattice expansion and may even fill pore defects, thus lowering leaks through the Pd films. Furthermore, this study suggests that a membrane exposed to a CO mixture should not be cycled between CO and non-CO environments, but rather run continuously for best performance. Additionally, the choice of Pd-alloy and metal composition should be considered in regard to its carbon solubility to best predict lifetime performance.

08 HYDROGEN↗
DOE OSTI2018

Temperature-dependent plastic deformation mechanisms of a Cu/steel transforming nanolamellar composite

Metallic nanolamellar composites possess unusually high strength owing to the high density interfaces that impede dislocation nucleation and migration. Meanwhile most nanolamellar composites show limited ductility in tension due to the lack of effective deformation mechanisms. Martensitic transformation, once multiplied with dislocations, can improve the work hardening efficiently during plastic deformation, leading to enhanced ductility. It is thereby of interest to investigate the mechanical behavior of nanolamellar composites that contain martensitic constituents. We here report on the temperature-dependent deformation mechanisms of a nanolamellar Cu/carbon-steel composite wire with a high volume fraction of retained austenite. Tensile tests at various temperatures reveal that the mechanical behavior of the composite is sensitive to temperature, analogous to the feature of deformation-induced martensitic transformation in steels with mechanically metastable austenite. In particular, a maximum uniform elongation of 63% is achieved at 180 degrees C. In situ synchrotron X-ray studies suggest that the deformation mechanisms of the composite are a result of the competition between transformation and slip of the retained austenite. Finally, a deformation mechanism map is proposed and the boundary between stress- and strain-induced martensitic transformation is clearly identified.

36 MATERIALS SCIENCE↗
DOE OSTI2019

The path towards functional nanoparticle-DNA origami composites

Nanoparticles (NPs) hold tremendous promise for diverse applications infields such as imaging, sensing, nanorobotics, and for optical and electronic materials. These applications often require precisely controlled interactions between multiple NPs or between NPs and other components. Hence, the organization of NPs into composite materials has been an active area of research. DNA origami nanotechnology offers a promising path forward with unparalleled control over complex nanoscale geometry and functionalization, programmed dynamic and mechanical properties, stimulus response to local or externally applied triggers, and capability of assembly into higher-order 1D, 2D, or 3D materials. Furthermore, DNA origami self-assembly is rapid and scalable, overcoming limitations of top-down NP organization methods. In this review, we outline the challenges, recent advances, and opportunities for NP-DNA origami composites. We go into depth on aspects of DNA origami that enhance materials function, such as dynamic actuation, and we discuss practical aspects involved in making NP-DNA composites. Whereas the vast majority of research in NP-DNA origami composite synthesis focuses on gold NPs, these methods can be generalized to other DNA-coated NPs, and therefore more broadly establish a path towards functional NP-DNA origami composites. We envision this review will serve as a guide to materials science and engineering researchers to pursue new materials based on NP-DNA composites.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

In-situ ionothermal synthesis of nanoporous carbon/oxide composites: A new key to functional separators for stable lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) with high energy density are promising for energy storage. However, conventional polypropylene-based separator cannot avoid polysulfides shuttling which impedes the practical application of LSBs. Herein, an in-situ ionothermal synthesis strategy that concurrently applies ionic liquid as the solvent, template and high-yield carbon source is proposed for the facile preparation of nanoporous carbon/oxide composite separator modifiers. The composites exhibit features of high polarity, self doping, oxygen vacancy, heteroatom doping, abundant defects and high electronic conductivity. Theoretical and experimental studies suggest that the composites can efficiently trap and convert polysulfides for high-performance LSBs. Indeed, in the composite-modified LSBs with next-generation roll-to-roll dry-processed high-loading sulfur cathodes, enhanced performance is achieved, revealing the effectiveness of the composites as functional materials towards separator modification. Therefore, the proposed strategy and its delivered nanoporous composites exhibit excellent versatility and practicality for high-performance LSBs.

25 ENERGY STORAGE↗
DOE OSTI2018

Computational investigation of arranged scintillating particle composites for fast neutron detection

Composite materials have the potential to play an important role in enabling high-performance and cost-effective neutron detectors for fundamental science, global security, and dosimetry applications. This work presents neutron and gamma transport simulation results on composites consisting of 6 Li-containing GS20 scintillator glass particles arranged in an organic matrix. These composites achieve high sensitivity for neutrons while suppressing signals from gamma rays. The simulations successfully identified optimal composite parameters such as particle size, geometry, and inter-particle pitch. This information is key to the subsequent fabrication and scale-up of the desired GS20-in-acrylic composite. Finally, the simulation results presented in this paper demonstrate that arranged composites can provide high neutron detection efficiency with gamma misidentification values of <1 in 10 6 gamma rays, assuming irradiation with a 252 Cf spontaneous fission source.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Lattice Matched Carbide–Phosphide Composites with Superior Electrocatalytic Activity and Stability

Composites of electrocatalytically active transition-metal compounds present an intriguing opportunity toward enhanced activity and stability. Here, to identify potentially scalable pairs of a catalytically active family of compounds, we demonstrate that phosphides of iron, nickel, and cobalt can be deposited on molybdenum carbide to generate nanocrystalline heterostructures. Composites synthesized via solvothermal decomposition of metal acetylacetonate salts in the presence of highly dispersed carbide nanoparticles show hydrogen evolution activities comparable to those of state-of-the-art non-noble metal catalysts. Investigation of the spent catalyst using high resolution microscopy and elemental analysis reveals that formation of carbide–phosphide composite prevents catalyst dissolution in acid electrolyte. Lattice mismatch between the two constituent electrocatalysts can be used to rationally improve electrochemical stability. Among the composites of iron, nickel, and cobalt phosphide, iron phosphide displays the lowest degree of lattice mismatch with molybdenum carbide and shows optimal electrochemical stability. Turnover rates of the composites are higher than that of the carbide substrate and compare favorably to other electrocatalysts based on earth-abundant elements. Lastly, our findings will inspire further investigation into composite nanocrystalline electrocatalysts that use molybdenum carbide as a stable catalyst support.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Molecular Insights into Novel Struvite–Hydrogel Composites for Simultaneous Ammonia and Phosphate Removal

Struvite (NH 4 MgPO 4 ·6H 2 O) mineralization is an effective technique for removing ammonium and phosphate species from wastewater. However, its wider use faces obstacles because of the copresence of various pollutants in wastewater and the additional requirement for magnesium to achieve proper supersaturation conditions. To address these challenges, this study developed novel mineral–hydrogel composites that can remove ammonium and phosphate simultaneously via heterogeneous struvite and calcium phosphate (CaP) mineralization in hydrogel matrices. The composites include in situ formed struvite and CaP mineral seeds, decreasing the nucleation energy barrier of struvite and CaP formation and promoting their heterogeneous nucleation kinetics even under undersaturation conditions in bulk solution. The dual struvite and CaP seeded composites can simultaneously reduce the ammonium and total phosphate concentrations up to 60% (26.3 mg of N/g) and 91% (9.54 mg of P/g), respectively. Furthermore, the average particle sizes in composites were increased from 6.12 to 14.8 nm after wastewater treatment. Moreover, various ions commonly existing in wastewater did not significantly interfere with the removal of ammonium and phosphate. Thus, these new mineral–hydrogel composites can provide an innovative way to lower nutrient levels before discharge to streams. Moreover, encapsulating ammonium and phosphate in mineral-hydrogel composites enables their upcycling in agricultural or biorefinery applications.

Cations↗
DOE OSTI2016

Formation of Nanoscale Composites of Compound Semiconductors Driven by Charge Transfer

Composites are a class of materials that are formed by mixing two or more components. These materials usually have new functional properties compared to their constituent materials. Traditionally composites are formed by self-assembly due to structural dissimilarities or by engineering different layers or structures in the material. In this work, we report the synthesis of a uniform and stoichiometric composite of CdO and SnTe with a novel nanocomposite structure stabilized by the dissimilarity of the electronic band structure of the constituent materials. The composite has interesting electronic properties which range from highly n-type in CdO to semi-insulating in the intermediate composition range to highly p-type in SnTe. This can be explained by the overlap of the conduction and valence band of the constituent compounds. Ultimately, our report identifies a new class of composite semiconductors in which nanoscale self-organization is driven and stabilized by charge transfer between constituent materials.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

Holistic Design Consideration of Metal–Organic Framework-Based Composite Membranes for Lithium–Sulfur Batteries

Metal–organic framework (MOF)-based membranes have received significant attention as separators for lithium–sulfur (Li–S) batteries because of their high porosities, well-defined and tailored structures, and other tunable features that are desirable for preventing the “shuttle effect” of soluble polysulfides. Because of the insulating nature of most MOFs, composite membranes are generally constructed by a combination of MOFs and electron-conductive materials. In this work, we examine the property–performance relation between MOF-based separators and Li–S batteries by systematically adjusting the electrical conductivity, thickness, and mass loading of the MOF-based composite. Beyond the commonly referenced trapping or blocking ability of MOFs toward polysulfides, we find that by fixing the thickness of the MOF-based composite coating layer (~40 μm) on a Celgard membrane, the electrical conductivity of the MOF composite layer is of paramount importance compared with the physical/ chemical trapping ability of polysulfides. However, the trapping ability of MOFs becomes indispensable when the thickness of the composite layer is small (e.g., ~20 μm), indicating the synergetic effects of the adsorption and conversion capabilities of the thin composite layer. Furthermore, this work suggests the importance of a holistic design consideration for a MOF-based membrane for long-life and high-energy-density Li–S batteries.

25 ENERGY STORAGE↗
DOE OSTI2022

Alginate–Sodium Sulfate Decahydrate Phase Change Composite with Extended Stability

Here, this study reports on the use of sodium alginate to effectively stabilize sodium sulfate decahydrate (Na 2 SO 4 ∙10H 2 O, SSD) based phase change material (PCM) for application as a thermal energy storage material. Alginate/SSD composite PCMs were prepared by blending SSD with different concentrations of alginate polymer. The resulting composite PCMs demonstrate high phase change enthalpy ~160 J/g and extended cycling stability compared to existing PCM composites. The analysis carried out by optical microscopy, X-ray scattering, and periodic density functional theory (DFT) calculations demonstrated that the stabilization effect was caused by the interplay between ionic and hydrogen bond interactions between the alginate and SSD. Additionally, the variation in mechanical properties of PCM composites with polymer concentrations made it possible to formulate a composite that maintains stable performance after 3D printing. The advanced properties make this composite a promising candidate for application as a thermal energy storage material.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Design and Integration of Flexible Sensor Matrix for in Situ Monitoring of Polymer Composites

Sensory polymer composites are highly desirable for applications such as in situ and real-time production processes and structural health monitoring, and for technologies that include human–machine interfaces for the next generation of Internet of Things. However, the development of these materials is still in its infancy: these materials have been reported, but large-scale fabrication of polymer composites with versatile and customizable sensing capabilities has yet to be demonstrated. Here, we report on a scalable fabrication strategy that enables such materials by designing and integrating PCB technology-inspired large-area flexible sensor matrices into polymer composites. The integrated sensor matrices successfully monitored in situ the production processes and structural health of an industrial polymer composite: from the application of vacuum, resin flow and polymerization, production defects, and temperature distribution. Our results demonstrate that the proposed strategy is a simple and effective solution as a distributed monitoring platform for polymer composites and shows the potential towards next generation of sensory polymer composites.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Elasticity-controlled jamming criticality in soft composite solids

Soft composite solids are made of inclusions dispersed within soft matrices. They are ubiquitous in nature and form the basis of many biological tissues. In the field of materials science, synthetic soft composites are promising candidates for building various engineering devices due to their highly programmable features. However, when the volume fraction of the inclusions increases, predicting the mechanical properties of these materials poses a significant challenge for the classical theories of composite mechanics. The difficulty arises from the inherently disordered, multi-scale interactions between the inclusions and the matrix. To address this challenge, we systematically investigated the mechanics of densely filled soft elastomers containing stiff microspheres. We experimentally demonstrate how the strain-stiffening response of the soft composites is governed by the critical scalings in the vicinity of a shear-jamming transition of the included particles. The proposed criticality framework quantitatively connects the overall mechanics of a soft composite with the elasticity of the matrix and the particles, and captures the diverse mechanical responses observed across a wide range of material parameters. The findings uncover a novel design paradigm of composite mechanics that relies on engineering the jamming properties of the embedded inclusions.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Impacts of glass composition, pH, and temperature on glass forward dissolution rate

Nuclear waste glasses dissolve at the forward dissolution rate (r f ) in very dilute aqueous solutions, which can isolate the impact of the glass composition from solution feedback and alteration product effects. While it has long been known that pH and temperature (T) strongly impact r f , the impacts of glass composition have remained uncertain. In this work, r f data from 19 nuclear waste glasses were used with the aim of identifying the effect of glass composition on r f . The r f values were modeled as: r f = k 0 10 –ηpH exp(-E a /RT), with k 0 , η, E a , and R, respectively, being the intrinsic rate constant, pH coefficient, apparent activation energy, and gas constant. However, no predictive correlation could be established between the individual model parameters (log[k 0 ], η, and E a ) and glass composition for the glasses considered in this study, an outcome that was attributed to the strong positive correlation between the log[$k_0$] and E a parameters. Therefore, a model was fitted directly to the combined r f from all 19 glasses. This approach showed that 90% of the variation in r f data could be accounted for solely by T and pH effects. Therefore, any composition effects must be relatively small. After normalizing for differences in pH and T, the only notable differences in r f between the glasses were found to correlate with variations in the fraction of glass forming tetrahedra contributed by tetrahedral boron, $f$([ 4 ]B), with an abrupt threshold at a high value of $f$([ 4 ]B) (~0.22), where higher r f are predicted with no discernable composition effects below the threshold.

36 MATERIALS SCIENCE↗
DOE OSTI2017

3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties

Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignment within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Moreover, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Biomass-derived monomers for performance-differentiated fiber reinforced polymer composites

Nearly all polymer resins used to manufacture critically important fiber reinforced polymer (FRP) composites are petroleum sourced. In particular, unsaturated polyesters (UPEs) are widely used as matrix materials and are often based on maleic anhydride, a four-carbon, unsaturated diacid. Typically, maleic anhydride is added as a reactant in a conventional step-growth polymerization to incorporate unsaturation throughout the backbone of the UPE, which is then dissolved in a reactive diluent (styrene is widely used) infused into a fiber mat and cross-linked. Despite widespread historical use, styrene has come under scrutiny due to environmental and health concerns; in addition, many conceivable UPEs are not soluble in styrene. In this study, we demonstrate that renewably-sourced monomers offer the ability to overcome these issues and improve overall composite performance. The properties of poly(butylene succinate)-based UPEs incorporating maleic anhydride are used as a baseline for comparison against UPEs derived from fumaric acid, cis , cis -muconate, and trans , trans -muconate, all of which can be obtained biologically. The resulting biobased UPEs are combined with styrene, methacrylic acid, or a mixture of methacrylic acid and cinnaminic acid, infused into woven fiberglass and cross-linked with the addition of a free-radical initiator and heat. This process produces a series of partially or fully bio-derived composites. Overall, the muconate-containing UPE systems exhibit a more favorable property suite than the maleic anhydride and fumaric acid counterparts. In all cases at the same olefinic monomer loading, the trans , trans -muconate polymers exhibit the highest shear modulus, storage modulus, and glass transition temperature indicating stronger and more thermally resistant materials. They also exhibit the lowest loss modulus indicating a greater adhesion to the glass fibers. The use of a mixture of methacrylic and cinnaminic acid as the reactive diluent results in a FRP composite with properties that can be matched to reinforced composites prepared with styrene. Significantly, at one-third the monomer loading (corresponding to two-thirds the number of double bonds), trans , trans -muconate produces approximately the same storage modulus and glass transition temperature as maleic anhydride, while exhibiting a superior loss modulus. Altogether, this work demonstrates the novel synthesis of performance-differentiated FRP composites using renewably-sourced monomers.

09 BIOMASS FUELS↗
DOE OSTI2017

Carbon nanotubes reinforced copper composite with uniform CNT distribution and high yield of fabrication

Dispersion of carbon nanotubes (CNTs) in metal matrix composites has been an unsolved issue since the discovery of CNTs. This paper presents a newly developed fabrication process of bulk Cu/CNT composite with uniformly distributed CNTs. That is, copper encapsulated CNTs powders were firstly fabricated by an electrochemical deposition where CNTs can be completely dispersed in the copper electrolyte assisted by sonication, and then the fabricated composite powders were used to make bulk Cu/CNT composite by a powder metallurgy process. The increment in microhardness of Cu/CNT composite after compaction and sintering was observed to be ~47.6% per 1% CNTs. The developed fabrication process of Cu/CNT composite powders by electrochemical co-deposition can be scaled up to meet specific application needs, and a similar process is expected to be applicable for other metals.

36 MATERIALS SCIENCE↗