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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 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Stoichiometric metal nitration based novel green synthesis of mesoporous metal oxides and their enhanced heterogeneity

Here, in this work, a general and novel method for the green synthesis of mesoporous metal oxides via stoichiometric metal nitration has been demonstrated. Pluronic surfactants and their effect on synthesis procedures in terms of surface area have been experimentally studied in detail. Contrary to the traditional synthesis procedure, water has been utilized as the solvent and in several cases, such as tin oxide, manganese oxide, aluminum oxide, antimony oxide, zinc oxide, cobalt oxide, copper oxide, yttrium oxide, lanthanum oxide, and silver either the highest or comparable surface areas have been successfully synthesized. Through XRD, and TEM, all materials were observed to be crystalline except silver and magnesium oxide. SEM shows that with an increase in surfactant molar mass agglomeration decreases. Ammonia chemisorption on acidic materials gives quantitative amounts of ammonia chemical bonding with catalysts, whereas carbon dioxide chemisorption gives a quantitative value of CO 2 chemical binding with basic sites. As high as 1901.8 μmol/g and 994.6 μmol/g ammonia chemisorption values for oxides of vanadium and tin were achieved. Amphoteric materials give both acidic and basic enhanced adsorption. Finally, all synthesized materials are studied under organic catalytic transformations. Benzyl bromide is theoretically more active compared with benzylamine and benzyl alcohol which was also experimentally shown through the conversion.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Heterogenized Pyridine-Substituted Cobalt(II) Phthalocyanine Yields Reduction of CO2 by Tuning the Electron Affinity of the Co Center

Conversion of CO 2 to reduced products is a promising route to alleviate irreversible climate change. In this paper we report the synthesis of a Co-based phthalocyanine with pyridine moieties (CoPc-Pyr), which is supported on a carbon electrode and shows Faradaic efficiency ~90% for CO at 490 mV of overpotential (-0.6 V vs reversible hydrogen electrode (RHE)). In addition, its catalytic activity at -0.7 V versus RHE surpasses other Co-based molecular and metal-organic framework catalysts for CO 2 reduction at this bias. Density functional theory calculations show that pyridine moieties enhance CO 2 adsorption and electron affinity of the Co center by an inductive effect, thus lowering the overpotential necessary for CO 2 conversion. Our study shows that CoPc-Pyr reduces CO 2 at lower overpotential and with higher activity than noble metal electrodes, such as silver.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Electrostatic Gating of Ionic Conductance through Heterogeneous van der Waals Nanopores

Nanofluidic ionic transistors typically require gate voltages above 1 V and operate only at submillimolar ionic strengths, limiting their biocompatible applications. We demonstrate ionic transistors consisting of single sub-10 nm nanopores drilled in van der Waals (vdW) heterostructures with internal gate electrodes made of few-layer graphene. These devices deliver up to 10-fold current modulation at gate voltages as low as 0.3 V in 10 mM KCl, and ∼2-fold modulation at near-physiological 100 mM KCl. Baseline conductance with no gate shows surface-charge-dominated transport below 100 mM KCl, consistent with negatively charged hBN walls and ∼5 nm opening of the pores. The surface charge and the electrochemical asymmetry introduced by the three-electrode configuration govern the device’s behavior: negative gate voltage (V G ) enriches ionic concentrations and enhances current, whereas positive V G induces a local depletion zone that suppresses transport. The current modulation by V G is dependent on the polarity of the transmembrane potential and leads to ion current rectification. Molecular dynamics simulations of a nanopore in a hBN–graphene–hBN stack reveal confinement and surface charge-dependent suppression of the relative permittivity of interfacial water. Continuum modeling with radially varying interfacial water permittivity reproduces the asymmetric I–V characteristics and explains how the embedded gate sculpts local potential and ion concentrations. By enabling sub-0.5 V control of ionic transport at up to 100 mM salt concentrations, these devices address a key need in nanofluidics to create low-power ionic circuits and biosensing.

Materials science↗
DOE OSTI2022

Liquid-Phase Effects on Adsorption Processes in Heterogeneous Catalysis

Aqueous solvation free energies of adsorption have recently been measured for phenol adsorption on Pt(111). Endergonic solvent effects of ~1 eV suggest solvents dramatically influence a metal catalyst’s activity with significant implications for the catalyst design. However, measurements are indirect and involve adsorption isotherm models, which potentially reduces the reliability of the extracted energy values. Computational, implicit solvation models predict exergonic solvation effects for phenol adsorption, failing to agree with measurements even qualitatively. In this study, an explicit, hybrid quantum mechanical/molecular mechanical approach for computing solvation free energies of adsorption is developed, solvation free energies of phenol adsorption are computed, and experimental data for solvation free energies of phenol adsorption are reanalyzed using multiple adsorption isotherm models. Explicit solvation calculations predict an endergonic solvation free energy for phenol adsorption that agrees well with measurements to within the experimental and force field uncertainties. Computed adsorption free energies of solvation of carbon monoxide, ethylene glycol, benzene, and phenol over the (111) facet of Pt and Cu suggest that liquid water destabilizes all adsorbed species, with the largest impact on the largest adsorbates.

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

Cascadia Subduction Zone Fault Heterogeneities From Newly Detected Small Magnitude Earthquakes

The Cascadia subduction zone (CSZ) is known to host M9 megathrust ruptures; however, no such event has occurred in historical observation. The distribution and characteristics of small- to moderate-sized earthquakes can be used to determine the behavior of the megathrust fault but are notably absent offshore the CSZ due to the distance from onshore seismometers. We use automated subspace detection coupled with an onshore-offshore seismic deployment to find small-magnitude earthquakes in the offshore seismogenic zone and analyze their locations in the context of interseismic locking and seismogenic zone extent. Here we detected and located 5,282 earthquakes, 4,096 of which had been previously undetected. We find that the downdip extent of the seismogenic zone as defined by interplate seismicity agrees with the 20% locking contour of the Schmalzle et al. (2014, https://doi.org/10.1002/2013GC005172) geodetic model and extends deeper than predicted by previous thermal models. We cannot determine the updip extent of the seismogenic zone; this may be due to a lack of templates for detection in the updip source area, stress shadows updip of asperity loading, and/or strong locking to the trench. We present a map of possible asperities determined by the small earthquakes in this study. Our asperity locations and extents show some, but not complete, agreement with the asperities modeled from the 1700 M9 rupture and geodetic locking models, and good agreement with the paleo-rupture extents determined from offshore turbidites and forearc basin-based asperity estimates. This highlights the need of continued offshore observations over time, and to elucidate fine-scale variation in locking.

58 GEOSCIENCES↗
DOE OSTI2024

Direct conversion of methane to aromatics and hydrogen via a heterogeneous trimetallic synergistic catalyst

Abstract Non-oxidative methane dehydro-aromatization reaction can co-produce hydrogen and benzene effectively on a molybdenum-zeolite based thermochemical catalyst, which is a very promising approach for natural-gas upgrading. However, the low methane conversion and aromatics selectivity and weak durability restrain the realistic application for industry. Here, a mechanism for enhancing catalysis activity on methane activation and carbon-carbon bond coupling has been found to promote conversion and selectivity simultaneously by adding platinum–bismuth alloy cluster to form a trimetallic catalyst on zeolite (Pt-Bi/Mo/ZSM-5). This bimetallic alloy cluster has synergistic interaction with molybdenum: the formed CH 3 * from Mo 2 C on the external surface of zeolite can efficiently move on for C-C coupling on the surface of Pt-Bi particle to produce C 2 compounds, which are the key intermediates of oligomerization. This pathway is parallel with the catalysis on Mo inside the cage. This catalyst demonstrated 18.7% methane conversion and 69.4% benzene selectivity at 710 °C. With 95% methane/5% nitrogen feedstock, it exhibited robust stability with slow deactivation rate of 9.3% after 2 h and instant recovery of 98.6% activity after regeneration in hydrogen. The enhanced catalytic activity is strongly associated with synergistic interaction with Mo and ligand effects of alloys by extensive mechanism studies and DFT calculation.

03 NATURAL GAS↗
DOE OSTI2020

Underpotential lithium plating on graphite anodes caused by temperature heterogeneity

Rechargeability and operational safety of commercial lithium (Li)-ion batteries demand further improvement. Plating of metallic Li on graphite anodes is a critical reason for Li-ion battery capacity decay and short circuit. It is generally believed that Li plating is caused by the slow kinetics of graphite intercalation, but in this paper, we demonstrate that thermodynamics also serves a crucial role. We show that a nonuniform temperature distribution within the battery can make local plating of Li above 0 V vs. Li 0 /Li + (room temperature) thermodynamically favorable. This phenomenon is caused by temperature-dependent shifts of the equilibrium potential of Li 0 /Li + . Supported by simulation results, we confirm the likelihood of this failure mechanism during commercial Li-ion battery operation, including both slow and fast charging conditions. This work furthers the understanding of nonuniform Li plating and will inspire future studies to prolong the cycling lifetime of Li-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2024

Trends and Heterogeneity in Electric Vehicle Economics: A French Case Study

The total cost of ownership of electric vehicles depends on both the behavior and economic context of the driver as well as the level of government support offered for electrified vehicles. In this work, we study both of these effects as they shift private vehicle costs and emissions benefits, focused on a case study of the faculty and staff commuters to the Cite Scientifique campus of the University of Lille. The modeling approach considers the net costs and emissions from switching each driver from an internal combustion engine vehicle to three electrified options: a hybrid electric, a plug-in hybrid, and a pure battery electric. Increasing government support or technology-induced cost declines of electric vehicles both improve the economics of electrified options and shift more drivers towards battery electrics as the preferred alternative to thermal vehicles.

ADVANCED PROPULSION SYSTEMS,ENERGY PLANNING, POLIC↗
DOE OSTI2021

SBIR Phase I Final Report, TACO: Distributed and Heterogeneous Sparse Compiler

Tensor algebra is a powerful tool for computing, but writing optimized codes that operate on sparse tensors can be very complex. This project enables a Tensor Algebra Compiler (TACO) that simplifies this task from man-years to man-days and extends TACO to support complex and large distributed systems. This report details the hypotheses, approaches used, and findings in this project.

97 MATHEMATICS AND COMPUTING↗