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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 OSTI2024

Interfacial Nanostructure and Hydrogen Bond Networks of Choline Chloride and Glycerol Mixtures Probed with X-ray and Vibrational Spectroscopies

The molecular distribution at the liquid-vapor interface and evolution of the hydrogen bond interactions in mixtures of glycerol and choline chloride are investigated using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Nanoscale depth profiles of supersaturated deep eutectic solvent (DES) mixtures up to ~2 nm measured by ambient-pressure XPS show the enhancement of choline cation (Ch + ) concentration by a factor of 2 at the liquid-vapor interface compared to the bulk. In addition, Raman spectral analysis of a wide range of DES mixtures reveals the conversion of gauche-conformer Ch + into the anti-conformer in relatively lower ChCl concentrations. Finally, the depletion of Ch + from the interface (probing depth = 0.4 nm) is demonstrated by aerosol-based velocity map imaging XPS measurements of glyceline and water mixtures. The nanostructure of liquid-vapor interfaces and structural rearrangement by hydration can provide critical insight into the molecular origin of the deep eutectic behavior and gas-capturing application of DESs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Red Light-Powered Nanowire Photochemical Diodes for Unassisted Hydrogen Evolution and Glycerol Valorization

Artificial photosynthesis via unassisted photochemical diodes is a promising approach for generating solar fuels. However, photoelectrochemical systems often degrade under solar diurnal cycling, and reliance on solar insolation exacerbates land use. Narrow-band LED illumination offers continuous and constant operation, enabling the vertical integration of stable photochemical diodes. In this study, 740 nm red light was investigated as the illumination source for silicon-based photochemical diodes integrating the hydrogen evolution reaction with the glycerol oxidation reaction (GOR), where replacing the oxygen evolution reaction with GOR increases attainable bias-free photocurrents. Increasing photovoltages, saturation current densities, and power conversion efficiencies were observed with increasing incident red light intensity. Under a red light intensity of 60 mW cm –2 , these systems are stable above 7.5 mA cm –2 for 6 days with periodic electrolyte refreshing. In conclusion, these results offer a promising prospect for red light-powered photochemical diodes that integrate other significant reduction reactions, such as CO 2 reduction.

Alcohols↗
DOE OSTI2023

Photochemical Diodes for Simultaneous Bias-Free Glycerol Valorization and Hydrogen Evolution

Artificial photosynthesis offers a route to producing clean fuel energy. However, the large thermodynamic requirement for water splitting along with the corresponding sluggish kinetics for the oxygen evolution reaction (OER) limits its current practical application. Here, we offer an alternative approach by replacing the OER with the glycerol oxidation reaction (GOR) for value-added chemicals. By using a Si photoanode, a low GOR onset potential of -0.05 V vs RHE and a photocurrent density of 10 mA/cm 2 at 0.5 V vs RHE can be reached. Coupled with a Si nanowire photocathode for the hydrogen evolution reaction (HER), the integrated system yields a high photocurrent density of 6 mA/cm 2 with no applied bias under 1 sun illumination and can run for over 4 days under diurnal illumination. In conclusion, the demonstration of the GOR-HER integrated system provides a framework for designing bias-free photoelectrochemical devices at appreciable currents and establishes a facile approach to artificial photosynthesis.

09 BIOMASS FUELS↗
DOE OSTI2023

Acoustic properties, elasticity, and equation of state of glycerol under pressure

Herein we employed high-pressure Brillouin scattering to study the pressure dependencies of acoustic modes of glycerol up to 14 GPa at 300 K. We observed longitudinal acoustic velocities and transverse acoustic velocities for the first time from 5 to 14 GPa. The results allow the determination of a complete set of elastic properties and an accurate determination of the pressure–volume (P–V) equation of state (EOS). EOS parameters, K 0 = 14.9 ± 1.8 GPa and K' 0 = 5.6 ± 0.5, were determined from fits to the data from ambient pressure to 14 GPa. Direct volume measurements of the P–V EOS are consistent with those determined by Brillouin scattering. A deviation from a Cauchy-like relationship for elastic properties was observed, and the pressure dependencies of the photoelastic constants and relaxation times were documented from 5 to 14 GPa. These results have broad implications for glass-forming liquids, viscoelastic theory, and mode coupling theory.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1982

Effect of hydrogen bonding on the vibrational dephasing time in glycerol

The vibrational dephasing of the methyl CH2 symmetric stretch mode in glycerol was directly measured over an extended temperature range using picosecond coherent Raman pump and probe spectroscopy. The dephasing time was found to increase dramatically as the temperature of the supercooled liquid was lowered. This observation is attributed to the increased hydrogen bonding with decreasing temperature which hinders the dephasing of the CH2 vibration by reducing molecular motions.

Dorsinville, R.↗
NASA NTRS1989

Model of early self-replication based on covalent complementarity for a copolymer of glycerate-3-phosphate and glycerol-3-phosphate

Glyceraldehyde-3-phosphate acts as the substrate in a model of early self-replication of a phosphodiester copolymer of glycerate-3-phosphate and glycerol-3-phosphate. This model of self-replication is based on covalent complementarity in which information transfer is mediated by a single covalent bond, in contrast to multiple weak interactions that establish complementarity in nucleic acid replication. This replication model is connected to contemporary biochemistry through its use of glyceraldehyde-3-phosphate, a central metabolite of glycolysis and photosynthesis.

Weber, Arthur L.↗
NASA NTRS1989

Model of early self-replication based on covalent complementarity for a copolymer of glycerate-3-phosphate and glycerol-3-phosphate

Glyceraldehyde-3-phosphate acts as the substrate in a model of early self-replication of a phosphodiester copolymer of glycerate-3-phosphate and glycerol-3-phosphate. This model of self-replication is based on covalent complementarity in which information transfer is mediated by a single covalent bond, in contrast to multiple weak interactions that establish complementarity in nucleic acid replication. This replication model is connected to contemporary biochemistry through its use of glyceraldehyde-3-phosphate, a central metabolite of glycolysis and photosynthesis.

Weber, Arthur L.↗
NASA NTRS1991

Rotation of ultrasonically levitated glycerol drops

Ultrasonic levitation is used to suspend single millimeter-size glycerol drops in a rectangular chamber. Audio-frequency laterally standing waves set up in the chamber are used to torque the suspended drops. The shape evolution of the drop under the combined effect of centrifugal forces and the acoustic radiation stress, along with its angular velocity are monitored, using video imaging and light scattering techniques. The results show good qualitative agreement with the theoretically predicted shape evolution as a function of angular velocity.

Biswas, A.↗
NASA NTRS1995

Scattering of water from the glycerol liquid-vacuum interface

Molecular dynamics calculations of the scattering of D2O from the glycerol surface at different collision energies are reported. The results for the trapping probabilities and energy transfer are in good agreement with experiments. The calculations demonstrate that the strong attractive forces between these two strongly hydrogen bonding molecules have only a minor effect on the initial collision dynamics. The trapping probability is influenced to a significant extent by the repulsive hard sphere-like initial encounter with the corrugated surface and, only at a later stage, by the efficiency of energy flow in the multiple interactions between the water and the surface molecules.

NASA Center ARC↗