Substrate recognition induces sequential electron transfer across subunits in the nitrogenase-like DPOR complex
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SEARCH · Engineering Papers
Results for “electronic transfer”
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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Rearrangement collisions. III - Electron transfer from atoms to fast protons
High energy rearrangement collision in which fast proton incident upon atom picks up electron
PARTICLE COLLISION↗
Replacing a Cysteine Ligand by Selenocysteine in a [NiFe]-Hydrogenase Unlocks Hydrogen Production Activity and Addresses the Role of Concerted Proton-Coupled Electron Transfer in Electrocatalytic Reversibility
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Improved thermally conducting electron transfer polymers
Development of polymers with improved heat transfer coefficients for use in encapsulating electronic modules is discussed. Chemical reactions for synthesizing the polymers are described and thermodynamic and physical properties are analyzed.
Jenkins, R. K.↗
Proton-Coupled Electron Transfer: The Engine of Energy Conversion and Storage
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Extracellular electron transfer across bio-nano interfaces for CO 2 electroreduction
Acetogenic bacteria represent a class of organisms capable of converting reducing equivalents and carbon dioxide into products with carbon–carbon bonds. Materials-based bio-electrochemical approaches are attractive for supplying biological organisms directly with grid-supplied electrons to convert carbon dioxide to value-added chemicals. Carbon nanotube-modified biocathodes have emerged as promising candidates for microbial electrosynthesis with high yields of carbon product formation, but a fundamental understanding of extracellular charge transfer at this electrode-biofilm interface is still lacking. Here, we utilize solid-state interfaces between semiconducting single-walled carbon nanotubes (s-SWCNT) and a model acetogenic bacterium for mechanistic studies of electro-catalytic CO 2 conversion to acetate. Studies of bacteria/s-SWCNT interactions in a transistor-based device suggest direct extracellular electron transfer (EET) at the bio-nano interface. Deuterium isotope labeling experiments confirmed that the availability of electrochemically produced H 2 as a redox mediator does not limit the efficiency of EET and CO 2 electro-reduction for C. ljungdahlii biofilms, suggesting the primary reducing equivalents are the electrons delivered across the electrode/bacterium interface or involvement of biological redox mediators. Additional isotope labeling studies demonstrate high Faradaic efficiency for CO 2 electro-reduction at the SWCNT/bacterium interface. These results provide important information about EET across the bacterium/material interface in a model biocathode.
77 NANOSCIENCE AND NANOTECHNOLOGY↗
Proton-Coupled Electron Transfer at the Surface of Polyoxovanadate-Alkoxide Clusters
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Selective Hydrogenation of Azobenzene to Hydrazobenzene via Proton-Coupled Electron Transfer from a Polyoxotungstate Cluster
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Water Confinement on Polymer Coatings Dictates Proton–Electron Transfer on Metal-Catalyzed Hydrogenation of Nitrite
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Proton-Coupled Electron Transfer at the Pu 5+/4+ Couple
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Observation of pressure-induced electron transfer in SnC 2 O 4
We examined the high pressure behavior of stannous oxalate via Raman and X-ray absorption spectroscopy (XAS) inside a diamond anvil cell. Phase transitions were observed to occur near 2.6 and 15 GPa which were reversible upon decompression to ambient conditions. When further pressurized above 15 GPa, the colorless material sustains irreversible chemical alterations and becomes bright red colored – darkening at higher pressures. Another irreversible phase transition occurred above 20 GPa. Concomitant with color change of the sample, we observed a softening of the ν(C–C) modes of the C 2 O 4 2- anion via Raman spectroscopy. We performed a separate XAS experiment which indicates that the Sn 2+ cation undergoes a partial reduction of the 2+ oxidation state with pressure which persists when the sample was depressurized to ambient conditions. Thus, electron density within the C–C bond in the oxalate anion appears to migrate toward the tin cation with pressure. This observation suggests that pressure can offer a very controllable means to vary cation–anion and unit cell dimensions (and thus the electric interactions causing electron movement) and thus the pressure-induced synthesis of novel materials.
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Methyl Viologen Lead Iodide for Photocatalytic Reductive Coupling of Aromatic Carbonyls via Proton-Coupled Electron Transfer
Organic–inorganic metal halides (OIMHs) have emerged as promising photocatalysts for organic transformations due to their excellent optoelectronic properties. However, their instability, particularly under protic conditions, has limited their broader applications. Here, we report that a facilely prepared methyl viologen lead iodide (MVPb 2 I 6 ) powder can efficiently catalyze the visible-light-driven reductive coupling of aromatic aldehydes and ketones in protic solvents. Remarkably, MVPb 2 I 6 retains its structural integrity after photoreduction, highlighting its robustness. These results suggest that incorporating quaternary pyridinium cations into the OIMHs can enhance their stability and expand their applicability in photocatalytic organic synthesis.
organic-inorganic hybrid composites↗
Influence of the proton relay spacer on hydrogen electrocatalysis by cobalt hangman porphyrins
A cobalt hangman porphyrin system with a phenyl spacer between the porphyrin ring and an internal carboxylic acid group as well as its non-hangman analogue were synthesized and utilized for the study of the proton-coupled electron transfer (PCET) kinetics attendant to electrocatalytic hydrogen evolution. Cyclic voltammetry (CV) together with simulations show that a short distance between the proton relay and the redox active cobalt center as well as the increased proton donating strength results in superior catalytic activity. Here, the mechanism of hydrogen generation is at the nexus of proton transfer–electron transfer (PTET) and concerted proton–electron transfer (CPET), as opposed to an ETPT mechanism that is characteristic of hangman systems with longer proton relay networks.
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NASA/DoD Aerospace Knowledge Diffusion Research Project. Paper 30: The electronic transfer of information and aerospace knowledge diffusion
Increasing reliance on and investment in information technology and electronic networking systems presupposes that computing and information technology will play a major role in the diffusion of aerospace knowledge. Little is known, however, about actual information technology needs, uses, and problems within the aerospace knowledge diffusion process. The authors state that the potential contributions of information technology to increased productivity and competitiveness will be diminished unless empirically derived knowledge regarding the information-seeking behavior of the members of the social system - those who are producing, transferring, and using scientific and technical information - is incorporated into a new technology policy framework. Research into the use of information technology and electronic networks by U.S. aerospace engineers and scientists, collected as part of a research project designed to study aerospace knowledge diffusion, is presented in support of this assertion.
Pinelli, Thomas E.↗
The electronic transfer of information and aerospace knowledge diffusion
Increasing reliance on and investment in information technology and electronic networking systems presupposes that computing and information technology will play a motor role in the diffusion of aerospace knowledge. Little is known, however, about actual information technology needs, uses, and problems within the aerospace knowledge diffusion process. The authors state that the potential contributions of information technology to increased productivity and competitiveness will be diminished unless empirically derived knowledge regarding the information-seeking behavior of the members of the social system - those who are producing, transferring, and using scientific and technical information - is incorporated into a new technology policy framework. Research into the use of information technology and electronic networks by U.S. aerospace engineers and scientists, collected as part of a research project designed to study aerospace knowledge diffusion, is presented in support of this assertion.
Pinelli, Thomas E.↗
Modeling electron transfer from the barrier in InAs/GaAs quantum dot-well structure
We study single electron tunnelling from the barrier in the binary InAs/GaAs quantum structure including quantum well (QW) and quantum dot (QD). The tunneling is described in the terms of localized/delocalized states and their spectral distribution. The modeling is performed by using the phenomenological effective potential approach for InAs/GaAs heterostructures. The results for the two and three-dimensional models are presented. We focus on the effect of QD-QW geometry variations. The relation to the PL experiments is shown.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Controlled electron transfer by molecular wires embedded in ultrathin insulating membranes for driving redox catalysis
Organic bilayers or amorphous silica films of a few nanometer thickness featuring embedded molecular wires offer opportunities for chemically separating while at the same time electronically connecting photo- or electrocatalytic components. Such ultrathin membranes enable the integration of components for which direct coupling is not sufficiently efficient or stable. Photoelectrocatalytic systems for the generation or utilization of renewable energy are among the most prominent ones for which ultrathin separation layers open up new approaches for component integration for improving efficiency. Recent advances in the assembly and spectroscopic, microscopic, and photoelectrochemical characterization have enabled the systematic optimization of the structure, energetics, and density of embedded molecular wires for maximum charge transfer efficiency. The progress enables interfacial designs for the nanoscale integration of the incompatible oxidation and reduction catalysis environments of artificial photosystems and of microbial (or biomolecular)-abiotic systems for renewable energy.
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Single-Electron Transfer Stabilizes Metastable Alane in a Bipyridine-Functionalized MOF Nanopore
Nanoconfinement of metastable hydrides such as alane (AlH 3 ) in functionalized porous frameworks represents a promising yet largely untapped strategy for high-capacity energy storage. Despite its potential, the underlying mechanisms responsible for the thermodynamic stabilization of metastable hydrides are poorly understood. Here, in this study, concepts from solution Lewis acid–base chemistry were applied to a crystalline metal–organic framework (MOF) to stabilize AlH 3 . The long-range order and synthetically versatile pore chemistry enabled us to reveal the intimate details of the hydride-host interactions. Powder X-ray diffraction (PXRD) of AlH 3 -infiltrated UiO-67bpy (Zr 6 O 4 (OH) 4 (bpydc) 6 ; bpydc 2– = 2,2′-bipyridine-5,5′-dicarboxylate) confirms that the framework maintains its crystallinity up to 250 °C and is stable under 70 MPa H 2 pressure. We find that thermodynamic stabilization arises from coupled single-electron and hydrogen-atom transfer from AlH 3 to bipyridine-containing linkers. Electron paramagnetic resonance detects a bipyridyl radical with an anisotropic g-tensor (g values of 2.00132, 2.00215, and 2.00275), consistent with Bader charge analysis predicting 0.82 e – transferred from the hydride to the MOF. These findings establish critical structure–property relationships underpinning AlH 3 stabilization and suggest general strategies for tuning the thermodynamics and kinetics of metastable materials.
Shivanna, Mohana [Sandia National Laboratories (SN↗