Search NASA⌕ Search

SEARCH · Search NASA

Results for “alkalinity”

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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Imidazoles and imidazolium cations with exceptional alkaline stability

The invention provides: imidazole and imidazolium compounds of formulas (I) and (II): polymers containing a plurality of imidazolium-containing repeating units of formula (III′): and membranes and devices comprising the polymers. Also provided are methods of making the inventive compounds and polymers.

Coates, Geoffrey W.↗
DOE OSTI2022

Polyaromatic electrolytes for alkaline membrane fuel cells

A polyaromatic electrolyte for a fuel cell electrode includes a structure represented by Formula 1, wherein in Formula 1, Ar is a neutral unit represented by one of Formula 2A and Formula 2B: The fuel cell electrode may include a catalyst suspended in the polyaromatic electrolyte.

Park, Eun Joo↗
DOE OSTI2022

Cycling protocol for alkaline batteries

A method of operating a battery comprises discharging a cathode comprising manganese dioxide to within a 2nd electron capacity of the manganese dioxide at a C-rate of equal to or slower than C/10, recharging the battery, and cycling the battery during use a plurality of times. The cathode is in a battery, and the battery comprises the cathode, an anode, a separator disposed between the anode and the cathode, and an electrolyte. The cathode comprises the manganese dioxide and a conductive carbon. The anode comprises: a metal component and a conductive carbon. The metal component can be a metal, metal oxide, or metal hydroxide, and the metal of the metal component can be zinc, lithium, aluminum, magnesium, iron, cadmium and a combination thereof.

Kolhekar, Snehal↗
DOE OSTI2023

Method for carbon dioxide capture and sequestration using alkaline industrial wastes

A method of sequestering gaseous carbon dioxide in which an oxide is carbonated by contacting it with a first aqueous carbonate solution to convert a portion of the oxide into a carbonate, which precipitates from solution. By converting the oxide to a solid carbonate, the CO 2 from the first carbonate solution is sequestered into the precipitate. At the same time, an aqueous hydroxide solution is formed. The aqueous hydroxide solution is contacted with gaseous carbon dioxide which sequesters the gaseous CO 2 into a second aqueous carbonate solution. The second solution so generated is then recycled back into the process and used to convert the oxide into the precipitated carbonate.

Wang, Bu↗
DOE OSTI2023

Facile, low-energy routes for the production of hydrated calcium and magnesium salts from alkaline industrial wastes

Divalent ions are extracted from solids by leaching to form a divalent ion-containing solution. The divalent ion-containing solution is subjected to concentration to form a concentrated divalent ion-containing solution. Precipitation of a divalent ion hydroxide salt is induced from the concentrated divalent ion-containing solution. In other cases, the concentrated divalent ion-containing solution is exposed to carbon dioxide to induce precipitation of a divalent ion carbonate salt.

Sant, Gaurav N.↗
DOE OSTI2023

Alkaline manganese redox flow battery with inhibitor

A redox flow battery includes a redox flow cell and a supply and storage system external of the redox flow cell. The supply and storage system includes first and second electrolytes for circulation through the redox flow cell. The first electrolyte is a liquid electrolyte having electrochemically active manganese species with multiple, reversible oxidation states in the redox flow cell. The electrochemically active manganese species may undergo reactions that cause precipitation of manganese oxide solids. The first electrolyte includes an inhibitor that limits the self-discharge reactions. The inhibitor includes an oxoanion compound.

Davenport, Timothy↗
DOE OSTI2026

Novel PtNi single-atom–nanocluster (SA–NC) ensembles promote Tafel kinetics and ampere-class AEM hydrogen evolution

The development of efficient, durable, and low-PGM electrocatalysts for the hydrogen evolution reaction (HER) in alkaline media is critical for next-generation electrolysis technologies. We report a facile two-step synthesis of highly dispersed PtNi and PtNi-nitride nanoclusters (NCs) (~2.3 nm) with ultralow Pt content (0.5 at.%) anchored on N-doped Vulcan carbon. Structural and compositional characterization via XAS, XPS, HAADF-STEM, HRTEM, and EDS mapping established key structure–activity relationships across varying Pt/Ni ratios and pyrolysis temperatures. The Pt0.5Ni0.5/C-750 catalyst, an ensemble of PtNi M-N-C type single-atom (SA) moieties with neighboring PtNi nanoclusters (NC), exhibited superior HER performance in alkaline media, achieving overpotentials of 30, 115, and 210 mV at 10, 100, and 500 mA cm−2, respectively. Despite at a lower Pt content, this novel SA–NC ensemble outperformed commercial Pt/C by ~36%. A standardized literature comparison with contemporary Pt- and Ru-doped analogues reveals the as-prepared Pt0.5Ni0.5/C-750 to sit at the apex of Tafel-limited kinetics and low overpotential at 100 mA cm−2. Tafel-limited Tafel slopes in both alkaline and acidic regimes confirm favorable proton recombination kinetics. Mass activities at 200 mV reached 13.8 and 18.84 A mgPt−1 in alkaline and acidic media, respectively. However, excessive nitridation (e.g., at 650 °C) adversely altered Pt electronic structure and HER kinetics. While Ni enhanced alkaline HER, acidic HER favored Ni-free analogues. Pt0.5Ni0.5/C-750 also demonstrated robust temperature responsiveness and 300-h operational stability at high current densities (0.5–1.0 A cm−2) in MEA tests. This work presents a scalable strategy for designing thermally responsive, durable, and compositionally tunable NC catalysts with neighboring SA moieties for alkaline electrolysis.

AEMWE↗
DOE OSTI2024

Bicarbonate-Carbonate Selectivity through Nanofiltration for Direct Air Capture of Carbon Dioxide

Direct air capture (DAC) of carbon dioxide is one approach among many proposed that is capable of offsetting hard-to-avoid emissions. In previous work, we developed the alkalinity concentration swing (ACS) method, which is driven through concentrating an alkaline solution that has been loaded with atmospheric CO 2 by desalination technologies, such as reverse osmosis or capacitive deionization. Though the ACS is promising in terms of energy usage and implementation, its absorption rate and water requirements are infeasible for a large-scale DAC process. Here, we propose an improvement on the ACS, the bicarbonate-enriched alkalinity concentration swing (BE-ACS), which selects bicarbonate ions from a stream of aqueous alkaline solution that has absorbed atmospheric CO 2 . The bicarbonate-rich stream is then concentrated, which greatly increases its CO 2 partial pressure, and then CO 2 is extracted from solution. We experimentally investigate the use of pressure-driven nanofiltration (NF) membrane-based separation to select bicarbonate ions over carbonate ions. We screen commercial membranes and select one high-performance membrane for detailed studies, quantifying its bicarbonate-carbonate selectivity factor and bicarbonate-passage factor. Feed pH, the combined concentration of aqueous CO 2 , bicarbonate, and carbonate species (or dissolved inorganic carbon), alkalinity, and permeation flux are systematically varied to study NF separation properties. We find that the selectivity factor, which exceeds 30 times in certain regimes, increases with higher feed pH and higher alkalinity. Lastly, the performance metrics of the selected NF membrane are input into a theoretical BE-ACS cycle analysis, and the required energy input and cycle capacity output are evaluated. Ideal cycle energy is found to be as low as around 250 kJ/mol, with opportunities identified for further decreases through process engineering and forward osmosis energy recovery.

animal feed↗