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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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Theoretical prediction of coordination environments and stability constants of lanthanum lactate complexes in solution

Using Density Functional Theory calculations in combination with explicit solvent and a continuum solvent model, this work sets out to understand the coordination environment and relevant thermodynamics of La(III)-lactate complexes. Calculations focus on the coordination modes for the complexes and changes in Gibbs free energy for complexation in solution. These results confirm that the α-hydroxyl group should be protonated, or at least hydrogen bonded to a water molecule, upon successive addition of the lactate ligand to the La(III) center using Bader's Atoms-in Molecules (AIM) approach. In addition, we present a straightforward method for predicting stability constants at the semi-quantitative level for La(III)-lactate complexes in solution. Furthermore, the proposed method could be particularly useful for prediction of lanthanide complex formation in various biochemical, environmental, and nuclear separations processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Enhanced adsorption of CO 2 at steps of ultrathin ZnO: the importance of Zn–O geometry and coordination

In this paper, the interaction between CO 2 and ultrathin ZnO supported on Au(111) has been studied using temperature programmed desorption (TPD) and density functional theory (DFT) calculations. We find that CO 2 binds weakly on the planar ZnO bilayer and trilayer surfaces, desorbing at T = 130 K. CO 2 binds more strongly at the steps formed between ZnO bilayers and trilayers, desorbing at T = 285–320 K depending upon the CO 2 exposure. The adsorption energies determined from DFT calculations for CO 2 on the ZnO planar surfaces and at the steps are ~5.8 and 19.0 kcal mol –1 , respectively, agreeing with the apparent activation energies of desorption (Ed) estimated based on the TPD peaks at the limit of low CO 2 exposures (7.7 and 19.5 kcal mol –1 , respectively). The DFT calculations further identify that the most stable adsorption configuration of CO 2 at the steps of ultrathin ZnO is facilitated by the geometry and coordination of the Zn cations and O anions near the step region. Specifically, the enhanced adsorption takes place via bonding of both the C and O atoms of the CO 2 molecule to the tri-fold coordinated O anions at the trilayer edge and to the neighboring Zn cations on the bilayer terrace, respectively, leading to CO 2 bending and formation of a carbonate-like species.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Evaluating the impacts of amino acids in the second and outer coordination spheres of Rh-bis(diphosphine) complexes for CO 2 hydrogenation

To explore the influence of a biologically inspired second and outer coordination sphere on Rh-bis(diphosphine) CO 2 hydrogenation catalysts, a series of five complexes were prepared by varying the substituents on the pendant amine in the P(Et) 2 CH 2 N R CH 2 P(Et) 2 ligands (P Et N R P Et ), where R consists of methyl ester modified amino acids, including three neutral (glycine methyl ester (GlyOMe), leucine methyl ester (LeuOMe), and phenylalanine methyl ester (PheOMe)), one acidic (aspartic acid dimethyl ester (AspOMe)) and one basic (histidine methyl ester (MeHisOMe)) amino acid esters. The turnover frequencies (TOFs) for CO 2 hydrogenation for each of these complexes were compared to those of the non-amino acid containing [Rh(depp) 2 ] + (depp) and [Rh(P Et N Me P Et ) 2 ] + (NMe) complexes. Each complex is catalytically active for CO 2 hydrogenation to formate under mild conditions in THF. Catalytic activity spanned a factor of four, with the most active species being the NMe catalyst, while the slowest were the GlyOMe and the AspOMe complexes. Finally, when compared to a similar set of catalysts with phenyl-substituted phosphorous groups, a clear contribution of the outer coordination sphere is seen for this family of CO 2 hydrogenation catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Coordination-supported organic polymers: mesoporous inorganic–organic materials with preferred stability

Here, a simple and versatile strategy, borrowing ideas from the chemistry of MOFs and COFs, is developed for the synthesis of coordination-supported organic polymers (COPs) via coordination between Al 3+ and 5-amino-8-hydroxyquinoline together with organic imine- or imide-based polycondensation. The COPs with high surface areas (up to 1123 m 2 g -1 ) and abundant mesopores (2.5 nm or 14 nm) possess good crystalline and porous structure after being soaked in boiling water.

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

A coordination-based model for transition metal alloy nanoparticles

We present a simple approach for predicting the relative energies of bimetallic nanoparticles spanning a wide-ranging combinatorial space, using only the identity and nearest-neighbor coordination number of individual metal atoms as independent parameters. By performing straightforward metal atom adsorption calculations on surface slab models, we parameterize expressions for the energy of metal atoms as a function of their coordination number in 21 bimetallic pairings of fcc metals. Here, we rigorously establish the transferability of our model by predicting relative energies of a series of nanoparticles across a large number of morphologies, sizes, atomic compositions, and arrangements. The model is particularly accurate in predicting atomic rearrangements at or near the metal surfaces, which is essential for its potential applications when studying segregation phenomena or dynamic processes in heterogeneous catalysis. By rapidly forecasting site stabilities with atomic specificity across generic structural and compositional features, our model is able to reverse engineer thermodynamically feasible motifs of active sites in bimetallic nanoparticles through robust property ⇔ structure relations.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Combinatorial design of multimeric chelating peptoids for selective metal coordination

Current methods for metal chelation are generally based on multidentate organic ligands, which are generated through cumbersome multistep synthetic processes that lack flexibility for systematically varying metal-binding motifs. Octadentate ligands incorporating hydroxypyridinone or catecholamide binding moieties onto a spermine scaffold are known to display some of the highest affinities towards f-elements. Enhancing binding affinity for specific lanthanide or actinide ions however, necessitates ligand architectures that allow for modular and high throughput synthesis. Here we introduce a high-throughput combinatorial library of 16 tetrameric N -substituted glycine oligomers (peptoids) containing hydroxypyridinone or catecholamide chelating units linked via an ethylenediamine bridge and, for comparison, we also synthesized the corresponding mixed ligands derived from the spermine scaffold: 3,4,3-LI(1,2-HOPO) 2 (CAM) 2 and 3,4,3-LI(CAM) 2 (1,2-HOPO) 2 . Coordination-based luminescence studies were carried out with Eu 3+ and Tb 3+ to begin probing the properties of the new ligand architecture and revealed higher sensitization efficiency with the spermine scaffold as well as different spectroscopic features among the structural peptoid isomers. Solution thermodynamic properties of selected ligands revealed different coordination properties between the spermine and peptoid analogues with Eu 3+ stability constants log β 110 ranging from 28.88 ± 3.45 to 43.97 ± 0.49. The general synthetic strategy presented here paves the way for precision design of new specific and versatile ligands, with a variety of applications tailored towards the use of f-elements, including separations, optical device optimization, and pharmaceutical development.

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↗
DOE OSTI2021

Ligand-coordinated Ir single-atom catalysts stabilized on oxide supports for ethylene hydrogenation and their evolution under a reductive atmosphere

In this work, we present a novel series of oxide-supported Ir-ligand single-atom catalysts (SACs) for ethylene hydrogenation. The SACs were created by a metal–ligand self-assembly strategy developed by our group, using one of two ligands, either 1,10-phenanthroline-5,6-dione (PDO) or 3,6-Di-2-pyridyl-1,2,4,5-tetrazine (DPTZ), on powder supports of either CeO 2 or MgO. Characterization by XAS, XPS, and CO adsorption proved that Ir exist principally as highly uniform, cationic single-atoms. Ir SACs show significantly higher durability and metal utilization efficiency than Ir nanoparticle (NP) catalysts during ethylene hydrogenation at 100 °C, as well as excellent stability, as no Ir aggregates were detected after >10 h reaction. The activity can be tuned by ligand and support effects: PDO and CeO 2 are superior to DPTZ and MgO, respectively. This tunability is attributed to differences in H 2 activation capability, which results from differences in support reducibility, electron density on Ir, and, potentially, the local coordination environment of Ir. The Ir SACs lose H 2 activation activity either under inert gas or under H 2 . Through XPS and in situ XAS studies, we attributed the former to the reversible loss of Ir hydride, which is the active species for H 2 activation, and the latter to irreversible over-hydrogenation and loss of Ir–O/N coordination. This work presents a new type of Ir hydrogenation SACs that are more durable, efficient, and tunable than supported Ir NPs, while more stable than homogeneous Ir complexes. It also offers fundamental understanding regarding ligand and support effects, as well as the evolution of Ir single-atoms under H 2 , instructing future design of stable, effective hydrogenation SACs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Heavy chalcogenide-transition metal clusters as coordination polymer nodes

While metal–oxygen clusters are widely used as secondary building units in the construction of coordination polymers or metal–organic frameworks, multimetallic nodes with heavier chalcogenide atoms (S, Se, and Te) are comparatively untapped. The lower electronegativity of heavy chalcogenides means that transition metal clusters of these elements generally exhibit enhanced coupling, delocalization, and redox-flexibility. Leveraging these features in coordination polymers provides these materials with extraordinary properties in catalysis, conductivity, magnetism, and photoactivity. In this perspective, we summarize common transition metal heavy chalcogenide building blocks including polynuclear metal nodes with organothiolate/selenolate or anionic heavy chalcogenide atoms. Based on recent discoveries, we also outline potential challenges and opportunities for applications in this field.

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

Highly soluble copper(ι) iodide-based hybrid luminescent semiconductors containing molecular and one-dimensional coordinated anionic inorganic motifs

Copper(I) iodide-based inorganic–organic hybrid semiconductors are considered promising materials for various optoelectronic applications. Here, using imidazolium bridged benzotriazoles as multidentate ligands, we designed and synthesized a series of all-in-one (AIO)-type CuI hybrid materials that hold both ionic and coordinate bonds at the interface of organic and inorganic modules. Their structures range from 0D clusters to 2D extended networks built on various molecular (0D) and chain-like (1D) anionic inorganic motifs that are interconnected through cationic ligands via multiple Cu–N bonds. Benefiting from their unique bonding nature, these compounds exhibit high stability towards heat and moisture and can be well dissolved in polar aprotic solvents. They emit low-energy light spanning from yellow to red color (550–625 nm). Finally, the electronic structure, emission mechanism, and effect of different coordination modes on their photophysical properties were studied using both experimental and theoretical methods, which has provided insight into the structure–property relationship of these inorganic–organic semiconductors.

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

Conformational dynamicity in a copper( ii ) coordination complex

The geometries of copper coordination complexes are intricately related to their electron transfer capabilities, but the role of dynamics in these processes are not fully understood. We have previously reported CuCl(dpa OMe ), a complex exhibiting conformational fluxionality in its Cu I state and rigidity upon oxidation to Cu II . Here, we report the synthesis and characterization of [CuCl(dpa SMe )] +/0 , a complex exhibiting relative rigidity in its CuI state and structural dynamics upon oxidation to Cu II . The dynamics of [CuCl(dpa SMe )] + were characterized via X-ray diffraction, cyclic voltammetry, and EPR spectroscopy, where temperature-dependent interconversion between trigonal bipyramidal and square pyramidal geometries is observed. Coupling these solid and solution-state characterization data enabled assignment of the coordination geometries involved. As a result, factors impacting these dynamics and their potential implications for electron transfer are discussed.

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

Making coordination networks ionic: a unique strategy to achieve solution-processable hybrid semiconductors

The development of high-performance, solution-processable semiconducting materials is crucial for the advancement of emerging clean-energy technologies such as light-emitting diodes and photovoltaics. While hybrid perovskites have shown considerable promise for implementation in these technologies, their reliance on toxic metals and relatively low stability towards moisture and chemical environments remain to be addressed. In this Chemistry Frontiers article, we describe a unique strategy to build nontoxic, robust and solution-processable hybrid semiconductors based on copper halide by incorporating ionic bonds in coordination complexes (molecular or extended network structures). Specifically, these compounds are made of anionic copper(I) halide and cationic organic ligands that form both coordinate and ionic bonds at the inorganic/organic interfaces and are referred to as all-in-one (AIO)-type structures. Here, the unique bonding nature renders the AIO-type structures with greatly enhanced solubility, excellent optical tunability and remarkable framework stability, all highly desirable for thin-film based optoelectronic devices. We will highlight the most recent progress in the development of this material group, including their design strategies, important properties and potential for clean-energy related applications. We will also briefly discuss the existing challenges and future outlook of these materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Data-driven based coordinated smart inverter control for distributed energy resources

Smart inverters (SI) for distributed energy resources (DER) are becoming popular since they have the ability to stabilize as well as restore the voltage and frequency of power systems. Aiming at establishing the mathematical models combined with SI control methods, multiple optimization methods are developed. However, the computational complexity of solving such a mathematical model with various uncertainties limits the real-time application of the SI control. To conquer this challenge, a data-driven-based SI control approach is developed to achieve coordinated control in the high penetration DER system. First, an optimization problem for maximizing the active power generation and minimizing the power loss is designed using the Volt/VAR control. To reduce the time consumption, the recurrent neural network (RNN) is proposed to model the relationship between the uncertainties and control actions during the offline site. The RNN with different sub-structures such as the long short-term memory cell and gated recurrent unit cell are included to enrich the diversity of features. In the last stage, different experiment comparisons, including multiple uncertainties maps and stateof- art machine learning methods, are conducted to verify the effectiveness of the proposed method based on the IEEE 123 bus power system. The results demonstrate that the proposed method can effectively achieve a rapid and coordinated control with a lower error rate.

Qiu, Wei↗
DOE OSTI2021

Modelling and control coordination scheme of a wind‐to‐hydrogen set for future renewable‐based power systems

New challenges regarding system stability and efficiency arise when power systems operate with a high penetration level of inverter‐based renewable sources (IBRSs) and few synchronous generators. Since IBRSs have been on the rise, to secure the stable operation of future power systems, IBRSs will be required to support systems without having to rely on remaining synchronous generators. Also, to efficiently manage the uncertainty of renewable production, power‐to‐gas technology can provide the required flexibility. This study proposes modelling and a control coordination scheme (CCS) of a wind‐to‐hydrogen (W2H) set to optimise electricity production from a variable‐speed wind turbine generator (WTG) while helping balance between supply and demand in a system. To achieve this, a grid‐forming (GFM) inverter‐based WTG is modelled and a set of electrolyser and fuel cell is integrated at the DC circuit of a GFM‐WTG to be coordinated. Furthermore, the CCS offers an opportunity to reduce the investment cost for deploying a W2H set by utilising the control capabilities of a WTG and reducing the need for an additional device. The performance of the proposed W2H set with the CCS was verified considering the variations in system load and wind speed by using Power System Computer Aided Design (PSCAD)/ElectroMagnetic Transients including Direct Current (EMTDC).

Kim, Jinho↗
DOE OSTI2023

Control coordination in inverter‐based microgrids using AoI‐based 5G schedulers

Abstract A coordinated set point automatic adjustment with correction enabled (C‐SPAACE) framework that uses 5G communication for real‐time control coordination between inverter‐based resources (IBR) in microgrids is proposed. Utilising slicing capability, 5G offers low‐latency communication to C‐SPAACE under normal conditions. However, given the multitude of power grid use cases, a certain 5G slice for C‐SPAACE may have access only to limited radio spectrum resources, which if not managed well, greatly undermines the communication needs of C‐SPAACE framework. Thus, optimally scheduling the available spectrum resources among IBRs in a sliced 5G network‐based C‐SPAACE framework becomes a critical problem. To address this issue, the authors utilise a novel age of information (AoI) metric and designs an AoI‐based 5G scheduler to provide low‐latency communication to C‐SPAACE. Following this, a co‐simulation environment is designed using PSCAD/EMTDC and Python to simulate a microgrid supported by 5G communication. Time‐domain simulation case studies are performed using the proposed co‐simulation environment to evaluate the performance of C‐SPAACE using 5G with both AoI‐based and other baseline (non‐AoI) schedulers.

Choudhury, Biplav↗
DOE OSTI2014

Change in atomic coordination in a heavily deformed metallic glass

The local structure around Ni and La atoms in Al{sub 85}Ni{sub 10}La{sub 5} amorphous powder after ball milling was investigated by X-ray absorption spectroscopy. A continuous decrease in coordination number of Ni and La as a function of milling time was observed, while the nearest neighbour distance and the mean square atomic displacement did not change, pointing at the creation of free volume around the Ni and La atoms. These structural changes resemble those of a liquid upon temperature increase. The results are described by a shear band model in which the coordination numbers of Ni and La are different within and outside a shear band.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗