Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Membrane Carbonation”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Electrolyzers for the reduction of carbon dioxide to formate

The present disclosure relates to an electrochemical flow cell that includes a gap positioned between an ion exchange membrane (IEM) and a cathode gas diffusion electrode (GDE), where the gap is positioned to contain a liquid and the gap has a thickness value, as defined by the distance between the IEM and the cathode GDE, of between greater than zero mm and less than about 2.0 mm. In some embodiments of the present disclosure, the gap may be between about 0.1 mm and about 1.0 mm.

Klein, Jr., Walter Ellis↗
DOE OSTI2026

Blended conventional and high oxygen permeability ionomers as a fuel cell electrode binder

Ionomer strongly influences the performance of proton exchange membrane fuel cells (PEMFCs), affecting catalyst activity and reactant transport within the electrodes. While recent work on high oxygen permeability ionomers (HOPI) has demonstrated improved performance compared to conventional perfluorosulfonic acid (PFSA) ionomers such as Nafion™, there have also been reports of increased cracking in fabricated electrodes. We investigated the effects of blending HOPI with Nafion™ ionomer dispersions when fabricating cathode catalyst layers (CCLs). Small-angle x-ray scattering suggests that the ionomers mix well, and adsorption measurements indicate that HOPI adsorbs less strongly to the carbon-supported platinum (Pt) catalyst, and in blends, the Nafion™ ionomer exhibits a greater degree of adsorption. Imaging CCLs revealed a decrease in crack formation in blended samples as HOPI content decreased, with 14% HOPI having the lowest crack density. In a membrane electrode assembly (MEA) using a high surface area carbon support, the 14% HOPI blend exhibited similar performance to 100% HOPI. However, similar performance enhancements were not achieved with a medium surface area carbon support. These findings suggest a path for low-crack CCLs with enhanced oxygen transport, while highlighting a need for further investigation of ionomer blending towards efficient and durable PEMFCs.

25 ENERGY STORAGE↗
DOE OSTI2022

Comparison of vapour pressure osmometry, freezing point osmometry and direct membrane osmometry for determining the osmotic pressure of concentrated solutions

Osmometry is the analytical method of measuring osmotic pressure ($π$) and related colligative properties. Accurately measuring $π$ is essential for applications that use osmosis, including drug delivery systems and water filtration methods such as forward osmosis. The three most common forms of directly or indirectly measuring $π$ are vapour pressure osmometry (VPO), freezing point osmometry (FPO), and direct membrane osmometry (DMO). In this report, the performance of VPO, FPO, and DMO are compared for various aqueous solutions, including small molecule and polymer solutes, and potentially more difficult samples such as concentrated, carbonated, or viscous solutions. Furthermore, potential problems with each of the three methods are examined. Good practices can avoid inaccuracies in DMO due to external concentration polarization and solute diffusion through the membrane. Similarly, it is important to be aware of and avoid weaknesses in VPO and FPO in order to obtain reliable results. Even with care, however, the three methods still give different values of $π$ for concentrated aqueous solutions.

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

Na 3 Zr 2 Si 2 PO 12 Solid Electrolyte Membrane for High‐Performance Seawater Battery

Abstract Seawater batteries (SWBs) have gained tremendous interest in the electrochemical energy storage research field because of their low cost, natural abundance, and potential use for long‐duration energy storage. Advancing a SWB to demonstration projects is plagued by the poor electrochemical performance stemming from the poor interfaces of the solid electrolyte (SE), as well as the structural and chemical instabilities and sluggish ionic transport properties. In this study, the anode compartment of a surrogate SWB is constructed with a Na | SE | hard carbon configuration, and tailored dopants are introduced into the Nasicon‐type Na 3 Zr 2 Si 2 PO 12 (NZSP) SE membrane. After doping with TiO 2 , a much more densely packed pellet with uniformly distributed porous structure is obtained. Changes in surface chemistry and local structure in the bulk are observed, which are believed to contribute to the improved ionic conductivity and higher critical current density of the TiO 2 ‐doped NZSP. Stable cycling performance with reversible capacities based on different Na storage mechanisms are also demonstrated.

25 ENERGY STORAGE↗
DOE OSTI2022

Thermally stable hydrocarbon-based anion exchange membrane and ionomers

An anion exchange membrane is composed of a copolymer of 1,1-diphenylethylene and one or more styrene monomers, such as 4-tert-butylstyrene. The copolymer includes a backbone substituted with a plurality of ionic groups coupled to phenyl groups on the backbone via hydrocarbyl tethers between about 1 and about 7 carbons in length. High-temperature conditions enabled by these copolymers enhance conductivity performance, making them particularly suitable for use in anion exchange membranes in fuel cells, electrolyzers employing hydrogen, ion separations, etc. The properties of the membranes can be tuned via the degree of functionalization of the phenyl groups and selection of the functional groups, such as quaternary ammonium groups. Several processes can be used to incorporate the desired ionic functional groups into the polymers, such as chloromethylation, radical bromination, Friedel-Crafts acylation and alkylation, sulfonation followed by amination, or combinations thereof.

Lee, Sangwoo↗
DOE OSTI2024

Thermally stable hydrocarbon-based anion exchange membrane and ionomers

An anion exchange membrane is composed of a copolymer of 1,1-diphenylethylene and one or more styrene monomers, such as 4-tert-butylstyrene. The copolymer includes a backbone substituted with a plurality of ionic groups coupled to phenyl groups on the backbone via hydrocarbyl tethers between about 1 and about 7 carbons in length. High-temperature conditions enabled by these copolymers enhance conductivity performance, making them particularly suitable for use in anion exchange membranes in fuel cells, electrolyzers employing hydrogen, ion separations, etc. The properties of the membranes can be tuned via the degree of functionalization of the phenyl groups and selection of the functional groups, such as quaternary ammonium groups. Several processes can be used to incorporate the desired ionic functional groups into the polymers, such as chloromethylation, radical bromination, Friedel-Crafts acylation and alkylation, sulfonation followed by amination, or combinations thereof.

Lee, Sangwoo↗
DOE OSTI2022

Continuous Production of Carbon-Supported and Surfactant-Free Pt-M (M=Fe, Co, Ni, and Cu) Nanocrystals for Catalyzing Oxygen Reduction

Scalable production of carbon-supported Pt-M (M=Co, Ni, and Fe) alloy nanocrystals is of great importance for their practical application as catalysts towards the oxygen reduction reaction (ORR), a process key to the operation of proton-exchange membrane fuel cells. Here we report the use of a fluidic device for the in situ nucleation and growth of Pt-M nanocrystals on a commercial carbon support in a continuous and scalable fashion. The use of dimethylformamide not only enables well dispersion of the carbon powders for the creation of a homogeneous reaction mixture but also helps reduce metal precursors for the heterogeneous nucleation and growth of nanocrystals on the carbon surface. The size, shape, and composition of the nanocrystals can all be tuned by changing the metal precursors added into the reaction mixture, resulting in Pt-M nanocrystals uniformly distributed across the surface of the carbon support. Among the nanocrystals, the carbon-supported Pt-Co nanocrystals show the highest ORR specific and mass activities at 0.9 V, demonstrating 11.4- and 8.8-fold enhancements over the state-of-the-art commercial Pt/C catalyst.

Electrochemistry↗
DOE OSTI2022

A Generic Sacrificial Layer for Wide-Range Freestanding Oxides with Modulated Magnetic Anisotropy

Freestanding oxide nanomembranes have promising applications because of their novel electronic states and flexible crystalline structures. Several materials have been developed as sacrificial layers to exfoliate thin films from substrates via wet-etching. However, these materials face great challenges in terms of either complicated crystalline structures or corrosive solutions. Herein, a new sacrificial material, SrCoO 2.5 , is presented, which can be coherently grown with wide-range strains and crystalline orientations and is also soluble in eco-friendly solutions such as acetic acid, vinegar, and even carbonated drinks. With SrCoO 2.5 as the sacrificial layer, high-quality freestanding ferromagnetic SrRuO 3 membranes are achieved from wide-range epitaxial strains and different crystalline orientations. By investigating the evolution of the magnetic properties of these samples, it is discovered that epitaxial strain causes a distinct modification of the magnetic anisotropy of (001) pc -oriented SrRuO 3 samples, while its influence on the (110) pc and (111) pc samples is insignificant. This study not only demonstrates the freestanding SrRuO 3 as a promising material for flexible spintronic devices, but also offers a great opportunity to engineer a wide range of strained and oriented complex oxides for novel freestanding electronics using this newly developed sacrificial material.

36 MATERIALS SCIENCE↗
DOE OSTI2020

A Robust, Scalable Platform for the Electrochemical Conversion of CO 2 to Formate: Identifying Pathways to Higher Energy Efficiencies

This work demonstrated a robust, scalable cell architecture for electroreduction of CO 2 (CO 2 R). An up to 90% faradaic efficiency for the conversion of CO 2 R to formate at 500 mA/cm 2 was realized at a 25 cm2 gas diffusion electrode (GDE) with a carbon-supported SnO 2 electrocatalyst. Furthermore, a 1.27 mm thick catholyte was used between the bipolar membrane and cathode GDE, which could be further reduced to tens of micrometers upon refinement. The deconvolution of the potential drop from each individual component/process guides the pathways to higher energy efficiencies of CO 2 R at this platform. Significant changes in the agglomerate size and aspect ratio on the electrode before and after an 11 h test were revealed by nano-CT, suggesting reduced CO 2 accessibility from electrode degradation. The versatility of this CO 2 R testing platform enables the ability to assess materials, components, and interactions at scales more in line with future devices.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2024

Cooperative Atomically Dispersed Fe–N 4 and Sn–N x Moieties for Durable and More Active Oxygen Electroreduction in Fuel Cells

One grand challenge for deploying porous carbons with embedded metal–nitrogen–carbon (M–N–C) moieties as platinum group metal (PGM)-free electrocatalysts in proton-exchange membrane fuel cells is their fast degradation and inferior activity. Here, we report the modulation of the local environment at Fe–N 4 sites via the application of atomic Sn–N x sites for simultaneously improved durability and activity. We discovered that Sn–N x sites not only promote the formation of the more stable D2 FeN 4 C 10 sites but also invoke a unique D3 SnN x –Fe II N 4 site that is characterized by having atomically dispersed bridged Sn–N x and Fe–N 4 . This new D3 site exhibits significantly improved stability against demetalation and several times higher turnover frequency for the oxygen reduction reaction (ORR) due to the shift of the reaction pathway from a single-site associative mechanism to a dual-site dissociative mechanism with the adjacent Sn site facilitating a lower overpotential cleavage of the O–O bond. This mechanism bypasses the formation of the otherwise inevitable intermediate that is responsible for demetalation, where two hydroxyl intermediates bind to one Fe site. Lastly, a mesoporous Fe/Sn-PNC catalyst exhibits a positively shifted ORR half-wave potential and more than 50% lower peroxide formation. This, in combination with the stable D3 site and enriched D2 Fe sites, significantly enhanced the catalyst’s durability as demonstrated in membrane electrode assemblies using complementary accelerated durability testing protocols.

36 MATERIALS SCIENCE↗
NASA NTRS1993

Preliminary analysis of a membrane-based atmosphere-control subsystem

Controlled ecological life supprot systems will require subsystems for maintaining the consentrations of atmospheric gases within acceptable ranges in human habitat chambers and plant growth chambers. The goal of this work was to develop a membrane-based atmosphere comntrol (MBAC) subsystem that allows the controlled exchange of atmospheric componets (e.g., oxygen, carbon dioxide, and water vapor) between these chambers. The MBAC subsystem promises to offer a simple, nonenergy intensive method to separate, store and exchange atmospheric components, producing optimal concentrations of components in each chamber. In this paper, the results of a preliminary analysis of the MBAC subsystem for control of oxygen and nitrogen are presented. Additionally, the MBAC subsystem and its operation are described.

Mccray, Scott B.↗
NASA NTRS1993

Novel use of positively charged nylon transfer membranes for trapping indoleacetic acid or other small anions during efflux from plant tissues

Positively charged nylon blotting membranes were used as an anion binding medium to trap [14C]indoleactic acid (IAA) as it exited cells at the basal ends of Coleus blumei L. stem and Zea mays L. coleoptile segments. Autoradiography was used to visualize where the [14C] that moved out of the cut ends was localized on the nylon membrane. Diffusion of [14C]IAA from the initial point of contact with the nylon membrane was minimal. Comparison of the autoradiograms with anatomical tissue prints of the cut ends of the segments was used to determine what tissues participate in IAA movement. The results of these initial studies were consistent with other reports suggesting that [14C]IAA movement was primarily associated with vascular tissues in both C. blumei stems and corn coleoptiles, but the resolution was not sufficient to identify which vascular tissues were involved in IAA transport. With further refinements, this technique could also be used for studying the movement of other small charged molecules through plant tissues.

NASA Discipline Plant Biology↗
DOE OSTI2022

Crosslinked Polyethyleneimine Gel Polymer Interface to Improve Cycling Stability of RFBs

Redox flow batteries are considered a promising technology for grid energy storage. However, capacity decay caused by crossover of active materials is a universal challenge for many flow battery systems, which are based on various chemistries. In this paper, using the vanadium redox flow battery as an example, we demonstrate a new gel polymer interface (GPI) consisting of crosslinked polyethyleneimine with a large amount of amino and carboxylic acid groups introduced between the positive electrode and the membrane. The GPI functions as a key component to prevent vanadium ions from crossing the membrane, thus supporting stable long-term cycling. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were conducted to investigate the effect of GPI on the electrochemical properties of graphitic carbon electrodes (GCFs) and redox reaction of catholyte. X-ray photoelectron spectroscopy (XPS) and 1 H nuclear magnetic resonance (NMR) spectra demonstrated that the crosslinked GPI is chemically stable for 100 cycles without dissolution of polymers and swelling in the strong acidic electrolytes. Results from inductively coupled plasma mass spectrometry (ICP-MS), Fourier-transform infrared (FTIR) spectroscopy, and energy-dispersive X-ray (EDX) spectroscopy proved that the GPI is effective in maintaining the concentration of vanadium species in their respective half-cells, resulting in improved cycling stability because of it prevents active species from crossing the membrane and stabilizes the oxidation states of active species.

Lim, Hyung-Seok↗
DOE OSTI2021

Fluorine-Free Precise Polymer Electrolyte for Efficient Proton Transport: Experiments and Simulations

Designing polymers with controlled nanoscale morphologies and scalable synthesis is of great interest in the development of fluorine-free materials for proton-exchange membranes in fuel cells. This study focuses on a precision polyethylene with phenylsulfonic acid branches at every fifth carbon, p5PhSA, with a high ion-exchange capacity (4.2 mmol/g). The polymers self-assemble into hydrophilic and hydrophobic co-continuous nanoscale domains. In the hydrated state, the hydrophilic domain, composed of polar sulfonic acid moieties and water, serves as a pathway for efficient mesoscopic proton conductivity. The morphology and proton transport of p5PhSA are evaluated under hydrated conditions using in situ X-ray scattering and electrochemical impedance spectroscopy techniques. Additionally, at 40 °C and 95% relative humidity, the proton conductivity of p5PhSA is 0.28 S/cm, which is four times greater than Nafion 117 under the same conditions. Atomistic molecular dynamics (MD) simulations are also used to elucidate the interplay between the structure and the water dynamics. The MD simulations show strong nanophase separation between the percolated hydrophilic and hydrophobic domains over a wide range of water contents. The percolated hydrophilic nanoscale domain facilitates the rapid proton transport in p5PhSA and demonstrates the potential of precise hydrocarbon-based polymers as processible and effective proton-exchange membranes.

36 MATERIALS SCIENCE↗
DOE OSTI2022

High-energy and low-cost membrane-free chlorine flow battery

Abstract Grid-scale energy storage is essential for reliable electricity transmission and renewable energy integration. Redox flow batteries (RFB) provide affordable and scalable solutions for stationary energy storage. However, most of the current RFB chemistries are based on expensive transition metal ions or synthetic organics. Here, we report a reversible chlorine redox flow battery starting from the electrolysis of aqueous NaCl electrolyte and the as-produced Cl 2 is extracted and stored in the carbon tetrachloride (CCl 4 ) or mineral spirit flow. The immiscibility between the CCl 4 or mineral spirit and NaCl electrolyte enables a membrane-free design with an energy efficiency of >91% at 10 mA/cm 2 and an energy density of 125.7 Wh/L. The chlorine flow battery can meet the stringent price and reliability target for stationary energy storage with the inherently low-cost active materials (~$5/kWh) and the highly reversible Cl 2 /Cl − redox reaction.

25 ENERGY STORAGE↗
DOE OSTI2020

Outer membrane vesicles catabolize lignin-derived aromatic compounds in Pseudomonas putida KT2440

Lignin is an abundant and recalcitrant component of plant cell walls. While lignin degradation in nature is typically attributed to fungi, growing evidence suggests that bacteria also catabolize this complex biopolymer. However, the spatiotemporal mechanisms for lignin catabolism remain unclear. Improved understanding of this biological process would aid in our collective knowledge of both carbon cycling and microbial strategies to valorize lignin to value-added compounds. Here, we examine lignin modifications and the exoproteome of three aromatic–catabolic bacteria: Pseudomonas putida KT2440, Rhodoccocus jostii RHA1, and Amycolatopsis sp. ATCC 39116. P. putida cultivation in lignin-rich media is characterized by an abundant exoproteome that is dynamically and selectively packaged into outer membrane vesicles (OMVs). Interestingly, many enzymes known to exhibit activity toward lignin-derived aromatic compounds are enriched in OMVs from early to late stationary phase, corresponding to the shift from bioavailable carbon to oligomeric lignin as a carbon source. In vivo and in vitro experiments demonstrate that enzymes contained in the OMVs are active and catabolize aromatic compounds. Taken together, this work supports OMV-mediated catabolism of lignin-derived aromatic compounds as an extracellular strategy for nutrient acquisition by soil bacteria and suggests that OMVs could pote

biological funneling↗
DOE OSTI2023

Ultrathin electron and proton-conducting membranes for nanoscale integrated artificial photosystems

Reducing the thickness of separation membranes without compromising their selectivity and robustness is the most effective way of maximizing the areal conductivity. This is especially important for the integration of visible light-driven water oxidation and carbon dioxide (or proton) reduction into a complete artificial photosystem on the shortest possible length scale – the nanoscale – because of the efficiency advantages over macroscale photosystems. In addition to their excellent separation property, ultrathin membranes of 10 nm thickness or less need to exhibit sufficient electrical and proton conductivity in order for the photocatalytic rates to keep up with the photon flux at maximum solar intensity. Furher, two materials, graphene and amorphous silica with embedded molecular wires, have emerged as promising ultrathin membranes for the development of nanoscale integrated solar-fuel systems. Moreover, electrically conducting metal–organic or covalent–organic frameworks can be used to fabricate high surface area-supports that enable the use of molecular catalysts and/or light absorbers at an adequate areal density for nanoscale integration with graphene membranes. Following an overview of the electron and proton conductivity of these ultrathin materials and recent examples of photoelectrocatalytic applications that take advantage of some but not all the properties that constitute a complete functional membrane, the status and future opportunities for complete nanoscale integrated photosystems featuring an ultrathin membrane are discussed.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

2,3-Butanediol recovery from fermentation broth using membrane pertraction

2,3-Butanediol (BDO) has gained immense interest for use as a platform chemical in the production of many important chemicals such as synthetic rubber, plasticizer, and octane boosters. Using BDO as a precursor for sustainable aviation fuel production may significantly reduce the carbon footprint of the airline industry. However, recovery of BDO is challenging due to its relatively low concentration (∼10 wt %) in fermentation broth and its high affinity for water. In this work, we developed a membrane pertraction process for BDO recovery from biomass derived fermentation broth. Different organic solvents such as hexanol and oleyl alcohol were investigated. With traditional solvent extraction, hexanol required a solvent to feed ratio of 10 to recover >90 % BDO, and oleyl alcohol could recover 35 % of BDO at the same ratio. BDO recovery of >90 % was demonstrated with pertraction; a BDO extraction rate of 15 g 1 m −2 h −1 was achieved using hexanol, and an extraction rate of 10 g 1 m −2 h −1 was achieved using oleyl alcohol. Impurities commonly found in fermentation broth did not affect the separation performance of the pertraction process. In conclusion, this work demonstrates pertraction as a low-footprint, scalable method for recovery of high-purity BDO from fermentation broth.

2,3 butanediol↗