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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 1,549 records · Page 86
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Operando probing dynamic migration of copper carbonyl during electrocatalytic CO2 reduction

Single crystals and shape-controlled nanocrystals are well known to exhibit facet-dependent catalytic properties. However, few studies have investigated how those nanocrystals evolve and (de)activate during reactions, calling for the development of nanoscale time-resolved operando methods. In this context, we have designed Cu nanocubes as a model system to elucidate the underlying driving force of dynamic nanocatalyst reconstruction during the CO2 reduction reaction (CO2RR). Operando electrochemical liquid-cell scanning transmission electron microscopy (EC-STEM) and synchrotron-based X-ray spectroscopy reveal the size- and potential-dependent complete transformation from (100)-oriented Cu@Cu2O nanocubes to polycrystalline metallic Cu nanograins under CO2RR conditions. In addition, machine learning-assisted operando four-dimensional STEM reveals that large Cu nanograins derived from nanocubes form mainly crystalline domains, while their smaller counterparts are more amorphous due to faster evolution kinetics. In situ Raman spectroscopy and density functional theory calculations suggest that CO drives the ejection of single Cu atoms, resulting in few-nanometre Cu clusters and the surface migration of highly mobile copper carbonyl (Cu–CO) species. Combined, these multimodal operando methods and theoretical approaches pave the way for understanding the complex structural evolution of energy-related nanocatalysts under electrochemical conditions.

Yang, Yao↗
DOE OSTI2023

Pre-ceramic polymer-assisted nucleation and growth of copper sulfide nanoplates

Abstract Polymer-derived ceramics derived from pre-ceramic polymers (PCPs), have access to several form factors and are highly tunable systems. Tunability can be further expanded with the incorporation of functional nanoparticle fillers throughout the matrix for advanced nanocomposite polymer-derived ceramic development. However, capping ligands used in nanoparticle syntheses mix unfavorably with PCPs, giving aggregated filler material and diminished properties. To control dispersion, secondary nanoparticle processing is performed by adhering PCP-miscible caps to the surface after synthesis. This often sacrifices size control established for small nanoparticles (<10 nm). Herein, we successfully eliminate the need for extra nanoparticle processing through the development of a one-pot, copper sulfide synthesis in which a PCP assists the stable formation of nanoparticles and serves as the final graft molecule. We monitor the success of this methodology and the PCP’s role in the reaction through several characterization methods probing both the nanoparticle core and polymer graft.

Loughney, Patricia A. (ORCID:0000000199472267)↗
DOE OSTI2016

Endothelial Antioxidant-1: A key mediator of Copper-dependent wound healing in vivo

Here, Copper (Cu), an essential nutrient, promotes wound healing, however, target of Cu action and underlying mechanisms remains elusive. Cu chaperone Antioxidant-1 (Atox1) in the cytosol supplies Cu to the secretory enzymes such as lysyl oxidase (LOX) while Atox1 in the nucleus functions as a Cu-dependent transcription factor. Using cutaneous wound healing model, here we show that Cu content (by X-ray Fluorescence Microscopy) and nuclear Atox1 are increased after wounding, and that wound healing with and without Cu treatment is impaired in Atox1 - / - mice. Experiments using endothelial cell (EC)-specific Atox1 - / - mice and gene transfer of nuclear-target Atox1 in Atox1 - / - mice reveal that Atox1 in ECs as well as transcription factor function of Atox1 are required for wound healing. Mechanistically, Atox1 - / - mice show reduced Atox1 target proteins such as p47phox NADPH oxidase and cyclin D1 as well as extracellular matrix Cu enzyme LOX activity in wound tissues. This in turn results in reducing O 2 - production in ECs, NFkB activity, cell proliferation and collagen formation, thereby inhibiting angiogenesis, macrophage recruitment and extracellular matrix maturation. Our findings suggest that Cu-dependent transcription factor/Cu chaperone Atox1 in ECs plays an essential role to sense Cu to accelerate wound angiogenesis and healing.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Search for ferromagnetic order in overdoped copper-oxide superconductors

In copper-oxides that show high-temperature superconductivity (HTS), the critical temperature (Tc) has a dome-shaped doping dependence. The cause of demise of both Tc and superfluid density ns on the overdoped side is a major puzzle. A recent study of transport and diamagnetism in a large number of overdoped La2-xSrxCuO4 (LSCO) films shows that this cannot be accounted for by disorder within the conventional Bardeen-Cooper-Schrieffer theory. This brings to focus an alternative explanation — competition of HTS with ferromagnetic order, fluctuating in superconducting samples and static beyond the superconductor-to-metal transition. Here, we examine this proposal by growing single-crystal LSCO thin films with doping on both sides of the transition by molecular beam epitaxy, and using polarized neutron reflectometry to measure their magnetic moments. In a heavily overdoped, metallic but non-superconducting LSCO (x = 0.35) film, the spin asymmetry of reflectivity shows a very small static magnetic moment (~2 emu/cm3). Less-doped, superconducting LSCO films show no magnetic moment in neutron reflectivity, both above and below Tc. Therefore, the collapse of HTS with overdoping is not caused by competing ferromagnetic order.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Au-iClick mirrors the mechanism of copper catalyzed azide–alkyne cycloaddition (CuAAC)

This report outlines the investigation of the iClick mechanism between gold(I)-azides and gold(I)-acetylides to yield digold triazolates. Isolation of digold triazolate complexes offer compelling support for the role of two copper(I) ions in CuAAC. In addition, a kinetic investigation reveals the reaction is first order in both Au(I)-N 3 and Au(I)-C≡C-R equivalent to C-R, thus second order overall. A Hammett plot with a ρ = 1.02(5) signifies electron-withdrawing groups accelerate the cycloaddition by facilitating the coordination of the second gold ion in a π-complex. Rate inhibition by the addition of free triphenylphosphine to the reaction indicates that ligand dissociation is a prerequisite for the reaction. The mechanistic conclusions mirror those proposed for the CuAAC reaction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Stability and self-passivation of copper vanadate photoanodes under chemical, electrochemical, and photoelectrochemical operation

We discuss how deployment of solar fuels technology requires photoanodes and that long term stability, can be accomplished using light absorbers that self-passivate under operational conditions. We recently reported that several copper vanadates are promising photoanode materials, and their stability and self-passivation is demonstrated through a combination of Pourbaix calculations and combinatorial experimentation.

14 SOLAR ENERGY↗
DOE OSTI2016

Different routes to methanol: Inelastic neutron scattering spectroscopy of adsorbates on supported copper catalysts

We have investigated methanol synthesis with model supported copper catalysts, Cu/ZnO and Cu/MgO, using CO/H 2 and CO 2 /H 2 as feedstocks. Under CO/H 2 both catalysts show chemisorbed methoxy as a stable intermediate, the Cu/MgO catalyst also shows hydroxyls on the support. Under CO 2 /H 2 the catalysts behave differently, in that formate is also seen on the catalyst. For the Cu/ZnO catalyst hydroxyls are present on the metal whereas for the Cu/MgO hydroxyls are found on the support. Furthermore, these results are consistent with a recently published model for methanol synthesis and highlight the key role of ZnO in the process.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Electrochemical behaviour of naked sub-nanometre sized copper clusters and effect of CO 2

The study of the electrochemical behavior (in the presence of N 2 or CO 2 ) of size-controlled naked Cu 5 and Cu 20 nanoclusters, prepared using a combination of gas-phase cluster ion sources, mass spectrometry, and soft-landing techniques, evidences some relevant results regarding the redox behavior of these sub-nanometre sized copper particles and the effect of CO 2 on them. Cu 20 nanoclusters show anodic redox processes occurring at much lower potential with respect to Cu 5 nanoclusters, which behave relatively similar to much larger Cu particles. However, Cu 5 nanoclusters coordinate effectively CO 2 (hydrogen carbonate) in solution, different from Cu 20 nanoclusters and larger Cu particles. This effect, rather than the redox behavior, is apparently connected to the ability of Cu 5 nanoclusters to reduce CO 2 under cathodic conditions at low overpotential. In conclusion, although preliminary, these results provide rather exciting indications on the possibility of realizing low overpotential electrocatalytic conversion of CO 2 .

36 MATERIALS SCIENCE↗
DOE OSTI2017

Characterization of defects in copper antimony disulfide

Copper antimony disulfide (CuSbS 2 ) has several excellent bulk optoelectronic properties for photovoltaic absorber applications. Here, we report on the defect properties in CuSbS 2 thin film materials and photovoltaic devices studied using several experimental methods supported by theoretical calculations.

14 SOLAR ENERGY↗
DOE OSTI2019

A unique copper coordination structure with both mono- and bi-dentate ethylenediamine ligands

The compound (ethylenediamine-N)-bis(ethylenediamine-N,N')-copper(II) bis(nitrate) is reported. It has an asymmetric unit containing Cu(II) penta-coordinating to two chelating ethylenediamine (en) and one monodentate en ligands with square-pyramidal-based geometry having severe trigonal distortion, together with two nitrate anions. It is the first crystallographic confirmation of the existence of penta-coordination with exclusively en ligands for any metal center, as well as the first monodentate en attached to Cu(II) seen in the solid state. It can be visualized as the penta-ammine effect realized solely with bi-amine ligands, defying the presumed necessity of mono-amines. X-ray crystallography establishes it to have P2 1 /c space group with a = 12.83 Å, b = 9.77 Å, c = 11.91 Å, and β = 94.8° (at 100 K). Spectroscopic analysis of this compound is consistent with the crystallographic assessment of the coordination chemistry, and it is found to be a S = 1/2 paramagnet.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Highly active copper catalyst obtained through rapid MOF decomposition

A decomposed copper based metal–organic framework containing amorphous Cu species was found to be a highly reactive carbon supported catalyst (a-Cu@C). This catalyst is active for reduction, oxidation, and N-arylation reactions without further tuning or optimization. Higher catalyst turnover numbers for each of these transformations are obtained when comparing a-Cu@C activity to similar Cu-based materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Atomic interface effect of a single atom copper catalyst for enhanced oxygen reduction reactions

The regulation of catalytic activity in the oxygen reduction reaction (ORR) is significant to the development of metal–air batteries and other oxygen involving energy conversion devices. Herein, we propose an atomic interface strategy to construct a single atom copper catalyst (denoted as Cu-SA/SNC) which exhibits enhanced ORR activity with a half-wave potential of 0.893 V vs. RHE in alkaline media. Moreover, synchrotron-radiation-based X-ray absorption fine structure (XAFS) investigations together with density functional theory (DFT) calculations reveal that the isolated bond-shrinking low-valence Cu (+1)–N 4 –C 8 S 2 atomic interface moiety serves as an active site during the ORR process, and the synergistic mechanism between the Cu species and the carbon matrix at the atomic interface plays a critical role in boosting the ORR efficiency, by adjusting the reaction free energy of intermediate adsorption. Furthermore, this atomic interface concept may provide an alternative methodology for the rational design of advanced oxygen electrode materials and new probability to improve their catalytic performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Elucidating metal and ligand redox activities of a copper-benzoquinoid coordination polymer as the cathode for lithium-ion batteries

A novel redox-active quinone-based organic building block 1,4-dicyano-2,3,5,6-tetrahydroxybenzene (LH 4 ) has been synthesized and used as a bridging ligand to form a new 1D copper-benzoquinoid coordination polymer [CuL(DMF) 2 ] n . The compound is able to deliver an initial capacity as high as 268 mA h g -1 at 30 mA g -1 (~C/2.5) when used as the cathode in Li batteries. Ex situ XPS and FT-IR reveal the involvement of both Cu and organic moieties in the multi-electron redox reaction. Cu K-edge XANES and EXAFS measurements confirm the change in the oxidation state and coordination environment of Cu during the discharge–charge process. In situ generated metallic nanoparticles have been observed by TEM. The obtained mechanistic understanding of the metal–organic electrode materials for Li-based batteries may pave the way for the design of next-generation energy-storage systems.

25 ENERGY STORAGE↗