Search NASA⌕ Search

SEARCH · Search NASA

Results for “carbonaceous precursors”

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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Demystifying In Situ Pyrolysis Chemistry for High-Performance Polyanionic Cathodes in Sodium-Ion Batteries

In this article, the carbon coating strategy has emerged as an indispensable approach to improve the conductivity of polyanionic cathodes. However, owing to the complex reaction process between precursors of carbon and cathode, establishing a unified screening principle for carbonaceous precursors remains a technical challenge. Herein, we reveal that carbonaceous precursor pyrolysis chemistry undeniably influences the formation process and performance of Na 3 V 2 (PO 4 ) 3 (NVP) cathodes from in situ insights. By investigating three types of carbonaceous precursors, it is found that O/H-containing functional groups can provide more bonding sites for cathode precursors and generate a reducing atmosphere by pyrolysis, which is beneficial to the formation of polyanionic materials and a uniform carbon coating layer. Conversely, excessive pyrolysis of functional groups leads to a significant amount of gas, which is detrimental to the compactness of the carbon layer. Furthermore, the substantial presence of residual heteroatoms diminishes graphitization. In this case, it is demonstrated that carbon dots (CDs) precursors with suitable functional groups can comprehensively enhance the Na+ migration rate, reversibility, and interface stability of the cathode material. As a result, the NVP/CDs cathode displays outstanding capacity retention, maintaining 92% after 10,000 cycles at a high rate of 50 C. Altogether, these findings provide a valuable benchmark for carbon source selection for polyanionic cathodes.

25 ENERGY STORAGE↗
DOE OSTI2022

Graphene coating on silicon anodes enabled by thermal surface modification for high-energy lithium-ion batteries

Silicon is a high-energy density anode material for lithium-ion batteries, but it possesses shortcomings such as poor electronic conductivity, interfacial instability and mechanical fracturing that hinder its battery cycling. Carbon coating has been an important strategy for stabilizing silicon anodes, but the effects of the silicon surface properties on carbon coating morphology and the consequent silicon cycling stability have not been clearly elucidated. Herein, we find that thermal oxidation of the silicon anodes followed by chemical vapor deposition of carbonaceous precursors leads to a well-ordered graphene coating, whereas disordered graphite coating is formed on the native silicon surface. Graphene-coated silicon exhibits superior cycling performance, retaining a discharge capacity of ~1300 mAh g -1 after 300 cycles, whereas the disordered graphite-coated silicon suffers continuous degradation, retaining only~600 mAh g -1 after 300 cycles. Cryogenic electron microscopy reveals the mechanism behind the difference in cycling stabilities; graphene coated silicon is able to withstand the large mechanical strains induced during extended cycling, whereas disordered graphite coating is ruptured, exposing silicon surfaces to the electrolyte, leading to extensive buildup of SEI and poor cycling performance. Characterization of the silicon surface reveals that thermal treatment yields an oxygen-rich surface layer, which is hypothesized to play a decisive role in dictating the carbon coating. This work highlights the effect of silicon surface properties on carbon coating microstructure, and presents thermal treatment as a facile avenue to attain graphene coating on silicon anodes.

25 ENERGY STORAGE↗
NASA NTRS2014

Investigation of Pyridine Carboxylic Acids in CM2 Carbonaceous Chondrites: Potential Precursor Molecules for Ancient Coenzymes

The distribution and abundances of pyridine carboxylic acids (including nicotinic acid) in eight CM2 carbonaceous chondrites (ALH 85013, DOM 03183, DOM 08003, EET 96016, LAP 02333, LAP 02336, LEW 85311, and WIS 91600) were investigated by liquid chromatography coupled to UV detection and high resolution Orbitrap mass spectrometry. We find that pyridine monocarboxylic acids are prevalent in CM2-type chondrites and their abundance negatively correlates with the degree of pre-terrestrial aqueous alteration that the meteorite parent body experienced. We also report the first detection of pyridine dicarboxylic acids in carbonaceous chondrites. Additionally, we carried out laboratory studies of proton-irradiated pyridine in carbon dioxide-rich ices (a 1:1 mixture) to serve as a model of the interstellar ice chemistry that may have led to the synthesis of pyridine carboxylic acids. Analysis of the irradiated ice residue shows that a comparable suite of pyridine mono- and dicarboxylic acids was produced, although aqueous alteration may still play a role in the synthesis (and ultimate yield) of these compounds in carbonaceous meteorites. Nicotinic acid is a precursor to nicotinamide adenine dinucleotide, a likely ancient molecule used in cellular metabolism in all of life, and its common occurrence in CM2 chondrites may indicate that meteorites may have been a source of molecules for the emergence of more complex coenzymes on the early Earth.

precursor molecules↗
NASA NTRS2014

Investigation of Pyridine Carboxylic Acids in CM2 Carbonaceous Chondrites: Potential Precursor Molecules for Ancient Coenzymes

The distribution and abundances of pyridine carboxylic acids (including nicotinic acid) in eight CM2 carbonaceous chondrites (ALH 85013, DOM 03183, DOM 08003, EET 96016, LAP 02333, LAP 02336, LEW 85311, and WIS 91600) were investigated by liquid chromatography coupled to UV detection and high resolution Orbitrap mass spectrometry. We find that pyridine monocarboxylic acids are prevalent in CM2-type chondrites and their abundance negatively correlates with the degree of pre-terrestrial aqueous alteration that the meteorite parent body experienced. We lso report the first detection of pyridine dicarboxylic acids in carbonaceous chondrites. Additionally, we carried out laboratory studies of proton-irradiated pyridine in carbon dioxide-rich ices (a 1:1 mixture) to serve as a model of the interstellar ice chemistry that may have led to the synthesis of pyridine carboxylic acids. Analysis of the irradiated ice residue shows that a comparable suite of pyridine mono- and dicarboxylic acids was produced, although aqueous alteration may still play a role in the synthesis (and ultimate yield) of these compounds in carbonaceous meteorites. Nicotinic acid is a precursor to nicotinamide adenine dinucleotide, a likely ancient molecule used in cellular metabolism in all of life, and its common occurrence in CM2 chondrites may indicate that meteorites may have been a source of molecules for the emergence of more complex coenzymes on the early Earth.

Pyridine Carboxylic↗
NASA NTRS2002

A IAB-Complex Iron Meteorite Containing Low-Ca Clinopyroxene: Northwest Africa 468 and its Relationship to Iodranites and Formation by Impact Melting

Northwest Africa 468 (NWA 468) is a new ungrouped, silicate-rich member of the IAB complex of nonmagmatic iron meteorites. The silicates contain relatively coarse (approximately 300 micron-size) grains of low-Ca clinopyroxene with polysynthetic twinning and inclined extinction. Low-Ca clinopyroxene is indicative of quenching from high temperatures (either from protoenstatite in a few seconds or high-temperature clinoenstatite in a few hours). It seems likely that NWA 468 formed by impact melting followed by rapid cooling to less than or equal to 660 C. After the loss of a metal-sulfide melt from the silicates, sulfide was reintroduced, either from impact-mobilized FeS or as an S2 vapor that combined with metallic Fe to produce FeS. The O-isotopic composition (delta O-17 = -1.39 %) indicates that the precursor material of NWA 468 was a metal-rich (e.g., CR) carbonaceous chondrite. Lodranites are similar in bulk chemical and O-isotopic composition to the silicates in NWA 468; the MAC 88177 lodranite (which also contains low-Ca clinopyroxene) is close in bulk chemical composition. Both NWA 468 and MAC 88177 have relatively low abundances of REE (rare earth elements) and plagiophile elements. Siderophiles in the metal-rich areas of NWA 468 are similar to those in the MAC 88177 whole rock; both samples contain low Ir and relatively high Fe, Cu and Se. Most unweathered lodranites contain approximately 20 - 38 wt. % metallic Fe-Ni. These rocks may have formed in an analogous manner to NWA 468 (i.e., by impact melting of metal-rich carbonaceous-chondrite precursors) but with less separation of metal-rich melts from silicates.

Rubin, Alan E.↗
NASA NTRS1989

Aqueous alteration on the hydrous asteroids - Results of EQ3/6 computer simulations

The two models of carbonaceous chondrite precursor material presently formulated to study the process of aqueous alteration in hydrous asteroids are based, in the first case, on the anhydrous mineralogy of CM chondrites, while the second is based on that of the CV chondrites. It is noted that the alteration mineralogy of the CM chondrites and their parent asteroids may be produced by starting with the anhydrous mineralogy of the same CM chondrites, at temperatures in the 1-25 C range, with a wide variety of rock/fluid ratios. The mineralogy of the important CI chondrites is reproducible through the alteration of either CM or CV anhydrous material, at temperatures in the 50-150 C.

Zolensky, Michael E.↗
NASA NTRS2002

Environment Conscious, Biomorphic Ceramics from Pine and Jelutong Wood Precursors

Environment conscious, biomorphic ceramics have been fabricated from pine and jelutong wood precursors. A carbonaceous preform is produced through wood pyrolysis and subsequent infiltration with oxides (ZrO2 sols) and liquid silicon to form ceramics. These biomorphic ceramics show a wide variety of microstructures, densities, and hardness behavior that are determined by the type of wood and infiltrants selected.

Singh, Mrityunjay↗
NASA NTRS2003

Reactive Processing of Environmentally Conscious, Biomorphic Ceramics from Natural Wood Precursors

Environmentally conscious, biomorphic ceramics (Ecoceramics) are a new class of materials that are manufactured from renewable resources and wastes. In this study, silicon carbide and oxide-based biomorphic ceramics have been fabricated from pine and jelutong wood precursors. A carbonaceous preform is produced through wood pyrolysis and subsequent infiltration with oxides (ZrO2 sols) and liquid silicon to form ceramics. These biomorphic ceramics show a wide variety of microstructures, densities, and hardness behavior that are determined by the type of wood and infiltrants selected.

Singh, M.↗
NASA NTRS2017

Pathways to Meteoritic Glycine and Methylamine

Glycine and methylamine are meteoritic water-soluble organic compounds that provide insights into the processes that occurred before, during, and after the formation of the Solar System. Both glycine and methylamine and many of their potential synthetic precursors have been studied in astrophysical environments via observations, laboratory experiments, and modeling. Despite these studies, the synthetic mechanisms for their formation leading to their occurrence in meteorites remain poorly understood. Typical 13C-isotopic values ((delta)13C) of meteoritic glycine and methylamine are 13C-enriched relative to their terrestrial counterparts; thus, analyses of their stable carbon isotopic compositions (13C/12C) may be used not only to assess terrestrial contamination in meteorites but also to provide information about their synthetic routes inside the parent body. Here, we examine potential synthetic routes of glycine and methylamine from a common set of precursors present in carbonaceous chondrite meteorites, using data from laboratory analyses of the well-studied CM2 Murchison meteorite. Several synthetic mechanisms for the origins of glycine and methylamine found in carbonaceous chondrites may be possible, and the prevalence of these mechanisms will largely depend on (a) the molecular abundance of the precursor molecules and (b) the levels of processing (aqueous and thermal) that occurred inside the parent body. In this work, we also aim to contextualize the current knowledge about gas-phase reactions and irradiated ice grain chemistry for the synthesis of these species through parent body processes. Our evaluation of various mechanisms for the origins of meteoritic glycine and methylamine from simple species shows what work is still needed to evaluate both the abundances and isotopic compositions of simpler precursor molecules from carbonaceous chondrites as well as the effects of parent body processes on those abundances and isotopic compositions. The analyses presented here combined with the indicated measurements will aid a better interpretation of quantitative analysis of reaction rates, molecular stability, and distribution of organic products from laboratory simulations of interstellar ices, astronomical observations, and theoretical modeling.

interstellar ice↗
NASA NTRS1994

The Strecker synthesis from interstellar precursors as a source of amino acids in carbonaceous chondrites: Deuterium retention during synthesis

Amino acids in the Murchison carbonaceous chondrite are anomalously enriched in deuterium. Synthesis in Strecker reactions from D-enriched interstellar precursors during low temperature aqueous alteration of the parent body has been proposed by Cronin et al. (1988) to account for the isotopic observations. To test this hypothesis, we have measured the retention of deuterium in the glycine, alanine, and alpha-amino isobutyric acid produced, respectively, by reactions of formaldehyde-D2, acetaldehyde-D4, and acetone-D6 with HCN and NH3 in water.

Lerner, N. R.↗
NASA NTRSDate not supplied

TPSAS-NF1676L-11382-DND

Long-range transport of ozone precursor species and carbonaceous aerosols emitted by wildfires may affect the atmospheric composition and regional climate far away from the location of the fires. Major outbreaks of fires occurred in 3 areas of Asia, Kazakhstan, Siberia, and Thailand, during the spring of 2008. Satellite and aircraft-based observations and trajectory studies have identified the transit of the plumes from these fires across the Pacific. We have conducted simulations of the effects of these fires on the atmospheric composition using the Real-time Air Quality Modeling System (RAQMS). RAQMS is a global scale meteorological and chemical modeling system with unified (stratosphere/troposphere) chemistry module. Model results, for example, indicate that increases of 10 ppbv in upper tropospheric ozone at 180W longitude and northern mid-latitudes in April, 2008 could be attributed to these fires. Large increases in aerosol optical depth due to carbonaceous aerosols are also seen nearer the fire location. Both tropospheric ozone and carbonaceous aerosols influence the atmospheric energy balance and climate. We use an off-line radiative transfer model along with the RAQMS chemical and aerosol analyses to calculate the direct radiative forcing during April, 2008, due to Asian wildfire emissions. Arctic indirect radiative forcing due to these emissions are evaluated using RAQMS aerosol extinction analyses in conjunction with MODIS retrievals of cloud liquid water and effective radius. We will discuss the radiative forcing results and the relative influences of the different fire events.

Murali Natarajan↗
NASA NTRS1981

The interstellar dust as a precursor of Ca,Al-rich inclusions in carbonaceous chondrites

Multiple dust components are considered as a source of the observed anomalies in meteoritic oxygen isotope compositions. It is pointed out that these anomalies are not due to an incomplete mixing of several dust or gas-plus-dust components in the solar nebula. If they were, other elements would display similar anomalies. The anomalies must therefore stem from differing degrees of incomplete exchange of oxygen isotopes between the primordial gas and dust components of the nebula. The dust is more likely to have been the component which was enriched with 0-16. Since the isotopic difference between dust and gas probably could not have been preserved if the dust was ever completely vaporized in the nebula, the Ca,Al-rich inclusions in carbonaceous chondrites are unlikely to be condensates, but instead are distillation residues.

Wood, J. A.↗
NASA NTRS2006

Laboratory Studies on the Formation of Carbon-Bearing Molecules in Extraterrestrial Environments: From the Gas Phase to the Solid State

A detailed knowledge of the formation of carbon-bearing molecules in interstellar ices and in the gas phase of the interstellar medium is of paramount interest to understand the astrochemical evolution of extraterrestrial environments (1). This research also holds strong implications to comprehend the chemical processing of Solar System environments such as icy planets and their moons together with the atmospheres of planets and their satellites (2). Since the present composition of each interstellar and Solar System environment reflects the matter from which it was formed and the processes which have changed the chemical nature since the origin (solar wind, planetary magnetospheres, cosmic ray exposure, photolysis, chemical reactions), a detailed investigation of the physicochemical mechanisms altering the pristine environment is of paramount importance to grasp the contemporary composition. Once these underlying processes have been unraveled, we can identify those molecules, which belonged to the nascent setting, distinguish molecular species synthesized in a later stage, and predict the imminent chemical evolution of, for instance, molecular clouds. Laboratory experiments under controlled physicochemical conditions (temperature, pressure, chemical composition, high energy components) present ideal tools for simulating the chemical evolution of interstellar and Solar System environments. Here, laboratory experiments can predict where and how (reaction mechanisms; chemicals necessary) in extraterrestrial environments and in the interstellar medium complex, carbon bearing molecules can be formed on interstellar grains and in the gas phase. This paper overviews the experimental setups utilized in our laboratory to mimic the chemical processing of gas phase and solid state (ices) environments. These are a crossed molecular beams machine (3) and a surface scattering setup (4). We also present typical results of each setup (formation of amino acids, aldehydes, epoxides; synthesis of hydrogen terminated carbon chains as precursors to complex PAHs and to carbonaceous dust grains in general; nitriles as precursor to amino acids).

Jamieson, C. S.↗
DOE OSTI2020

The carbon content of Earth and its core

Earth’s core is likely the largest reservoir of carbon (C) in the planet, but its C abundance has been poorly constrained because measurements of carbon’s preference for core versus mantle materials at the pressures and temperatures of core formation are lacking. Using metal–silicate partitioning experiments in a laser-heated diamond anvil cell, we show that carbon becomes significantly less siderophile as pressures and temperatures increase to those expected in a deep magma ocean during formation of Earth’s core. Based on a multistage model of core formation, the core likely contains a maximum of 0.09(4) to 0.20(10) wt% C, making carbon a negligible contributor to the core’s composition and density. However, this accounts for ~80 to 90% of Earth’s overall carbon inventory, which totals 370(150) to 740(370) ppm. The bulk Earth’s carbon/sulfur ratio is best explained by the delivery of most of Earth’s volatiles from carbonaceous chondrite-like precursors.

Geosciences↗
DOE OSTI2020

De novo fabrication of multi-heteroatom-doped carbonaceous materials via an in situ doping strategy

Finding a succinct strategy to fabricate multi-heteroatom-doped nanoporous carbonaceous materials is a long-term challenge and highly desired research topic. The key to success is the rational design of easy to obtain and functionalized precursors. Herein, de novo fabrication of carbonaceous materials doped with multiple heteroatoms namely boron, nitrogen, oxygen, fluorine, and sulfur was achieved via a one-step in situ doping procedure using task-specific ionic liquids (TSILs) as precursors. Our strategy hinges on the adoption of particularly designed TSILs with structures functionalized with (1) boron source-containing anions, (2) imidazolium functionalities as the carbon and nitrogen source, (3) nitrile groups capable of trimerization during the heating process, and (4) bis(trifluoromethanesulphonyl)imide and related anions performing as the source of heteroatoms (i.e., fluorine, nitrogen, sulfur, and oxygen) and porogens. The unique structures of the as-prepared TSILs make them qualified precursors for the production of multi-heteroatom-doped carbonaceous materials through simple thermal treatment, with surface areas up to 1021 m 2 g -1 . The introduction of multiple heteroatoms provides the carbonaceous materials with efficient adsorption performance for the capture of hazardous anionic pollutants, dyes, and neutral organic molecules. This finding expands the versatility of TSILs with multi-functionalized architectures, delivering nanoporous materials with wide applications.

36 MATERIALS SCIENCE↗
NASA NTRS1998

Enantiomeric Excesses of Acid Labile Amino Acid Precursors of the Murchison Meteorite

Amino acids present in carbonaceous chondrite are extracted in water in part as free compounds and in approximately equal part as acid labile precursors. On the assumption that they would be free of contamination, the precursors of two Murchison amino acids that have terrestrial occurrence, alanine and glutamic acid, have been targeted for analysis of their enantiomeric ratios. Pyroglutamic acid, the precursor of glutamic acid, was found with an L-enantiomeric excess comparable to that of the free acid, while alanine's precursor, N-acetyl alanine, appears approximately racemic. Also alpha-imino propioacetic acid, a proposed end product of alanine synthesis in the meteorite, was analyzed and found racemic.

Pizzarello, Sandra↗
DOE OSTI2025

Resonance-stabilized radical clustering bridges the gap between gaseous precursors and soot in the inception stage

Carbonaceous particles are widespread in combustion, atmospheric, extraterrestrial, and nanomaterials environments. Resonance-stabilized radicals (RSRs) are commonly identified in fuel combustion and pyrolysis processes and play an essential role in carbonaceous particle formation. Despite their importance, comprehensive experimental and mechanistic understanding of particle inception through RSR reactions is lacking. This work investigated particle size distribution, chemical composition, and thermal behavior of soot particles generated by the flow reactor pyrolysis reactions of typical RSRs, in particular, 1-indenyl, 1-methylnaphthyl, and 2-methylnaphthyl radicals, and by the pyrolysis of hydrocarbons with a variety of structures. Particle size distributions show soot particles with mobility diameters in an incipient-particle range of 1.3 to 1.6 nm. Laser desorption/ionization mass spectrometry results suggest that soot products consist of much larger covalently bound clusters (CBCs) than those observed in the gas phase. Under our experimental conditions, the CBCs exhibit a phase transition for particles with calculated molecular diameters of around 1.5 nm. Evaporation experiments and thermogravimetric analysis of the soot products reveal distinct thermal characteristics for small and large CBCs. These results implicate CBCs as bridges between gas-phase species and soot particles. The present work provides a soot-inception mechanism called RSR clustering (RSRC) that is characterized by the reactive clustering of RSRs. The RSRC mechanism contrasts with conventional soot formation models that attribute soot inception primarily to the aggregation of large-size polycyclic aromatic hydrocarbons.

carbonaceous particle↗
NASA NTRS2017

Synthesis of Amino Acid Precursors with Organic Solids in Planetesimals with Liquid Water

Amino acids are important ingredients of life that would have been delivered to Earth by extraterrestrial sources, e.g., comets and meteorites. Amino acids are found in aqueously altered carbonaceous chondrites in good part in the form of precursors that release amino acids after acid hydrolysis. Meanwhile, most of the organic carbon (greater than 70 weight %) in carbonaceous chondrites exists in the form of solvent insoluble organic matter (IOM) with complex macromolecular structures. Complex macromolecular organic matter can be produced by either photolysis of interstellar ices or aqueous chemistry in planetesimals. We focused on the synthesis of amino acids during aqueous alteration, and demonstrated one-pot synthesis of a complex suite of amino acids simultaneously with IOM via hydrothermal experiments simulating the aqueous processing

Kebukawa, Y↗