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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 1,351 records · Page 75
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Single-Crystalline SrRuO 3 Nanomembranes: A Platform for Flexible Oxide Electronics

The field of oxide electronics has benefited from the wide spectrum of functionalities available to the ABO 3 perovskites, and researchers are now employing defect engineering in single crystalline heterostructures to tailor properties. However, bulk oxide single crystals are not conducive to many types of applications, particularly those requiring mechanical flexibility. Here, we demonstrate the realization of an all-oxide, single-crystalline nanomembrane heterostructure. With a surface-to-volume ratio of 2 × 10 7 , the nanomembranes are fully flexible and can be readily transferred to other materials for handling purposes or for new materials integration schemes. Using in situ synchrotron X-ray scattering, we find that the nanomembranes can bond to other host substrates near room temperature and demonstrate coupling between surface reactivity and electromechanical properties in ferroelectric nanomembrane systems. Finally, the synthesis technique described here represents a significant advancement in materials integration and provides a new platform for the development of flexible oxide electronics.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microscale-Resolution Thermal Mapping Using a Flexible Platform of Patterned Quantum Sensors

Here, temperature sensors with micro- and nanoscale spatial resolution have long been explored for their potential to investigate the details of physical systems at an unprecedented scale. In particular, the rapid miniaturization of transistor technology, with its associated steep boost in power density, calls for sensors that accurately monitor heating distributions. Here, we report on a simple and scalable fabrication approach, based on directed self-assembly and transfer-printing techniques, to constructing arrays of nanodiamonds containing temperature-sensitive fluorescent spin defects. The nano-particles are embedded within a low-thermal-conductivity matrix that allows for repeated use on a wide range of systems with minimal spurious effects. Additionally, we demonstrate access to a wide spectrum of array parameters ranging from sparser single-particle arrays, with the potential for quantum computing applications, to denser devices with 98 ± 0.8% yield and stronger photoluminescence signals, ideal for temperature measurements. With these, we experimentally reconstruct the temperature map of an operating coplanar waveguide to confirm the accuracy of these platforms.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Plasma-Initiated Graft Polymerization of Acrylic Acid onto Fluorine-Doped Tin Oxide as a Platform for Immobilization of Water-Oxidation Catalysts

The discovery of new and versatile strategies for the immobilization of molecular water-oxidation catalysts (WOCs) is crucial for developing clean energy conversion devices [e.g., (photo)electrocatalytic cells for water splitting]. The traditional approach for surface attachment to transparent conductive oxides [e.g., fluorine doped tin oxide (FTO)] is via synthetic modification of the ligand architecture to incorporate functional groups such as carboxylic acids (-COOH) or phosphonates (-PO 3 H 2 ) prior to immobilization. However, challenges arising from desorption and the cumbersome derivatizations steps have limited the scope and applications of surface-bound WOCs. Herein, we report the successful immobilization of underivatized Ru(II)-based WOCs (Ru–Cat1 = [Ru(tpy) (bpy) (H 2 O)] 2+ (tpy = 2,2':6'2"–terpyridine and bpy = 2,2;-bipyridine) and Ru–Cat2 = [Ru(Mebimpy) (bpy) (H 2 O)] 2+ (Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl) pyridine)) and the Ru(II) polypyridyl chromophore Ru–C3 = [Ru(bpy) 3 ] 2+ onto a FTO plasma-grafted poly(acrylic acid) surface (PAA|FTO). Various characterization techniques such as attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and cyclic voltammetry measurements provide evidence for the plasma-induced grafted PAA|FTO film and immobilization. Surface stability and electrocatalytic properties of these new hybrid composite films upon cycling were investigated at different pH values. Immobilized Ru–Cat1 and Ru–Cat2 onto PAA|FTO displayed pH-dependent (RuIII/RuII) couples and onset potentials indicative of PCET (proton-coupled electron transfer) reactions. Based on cyclic voltammetry results and spectroscopic monitoring, the immobilized WOCs Ru–Cat1 and Ru–Cat2 exhibited a higher surface stability in neutral aqueous solutions relative to Ru–C3 upon electrochemical oxidation. Furthermore, we attribute the surface PCET and stability to the presence of a water ligand in the coordination sphere of immobilized Ru–Cat1 and Ru–Cat2 which can H-bond with negatively charged carboxylate groups of the cross-linked PAA brushes. Our findings demonstrate that the plasma-grafted polymeric network onto FTO offers a versatile platform to directly anchor unmodified homogeneous WOCs or chromophores for potential applications in solar-to-fuel energy conversion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Low-Temperature 2D/2D Ohmic Contacts in WSe 2 Field-Effect Transistors as a Platform for the 2D Metal–Insulator Transition

in this work, we report the fabrication of hexagonal-boron-nitride (hBN) encapsulated multiterminal WSe 2 Hall bars with 2D/2D low-temperature Ohmic contacts as a platform for investigating the two-dimensional (2D) metal-insulator transition. We demonstrate that the WSe 2 devices exhibit Ohmic behavior down to 0.25 K and at low enough excitation voltages to avoid current-heating effects. Additionally, the high-quality hBN-encapsulated WSe 2 devices in ideal Hall-bar geometry enable us to accurately determine the carrier density. Measurements of the temperature (T) and density (n s ) dependence of the conductivity σ(T, n s ) demonstrate scaling behavior consistent with a metalinsulator quantum phase transition driven by electron-electron interactions, but where disorder-induced local magnetic moments are also present. Our findings pave the way for further studies of the fundamental quantum mechanical properties of 2D transition metal dichalcogenides using the same contact engineering.

2D materials↗
DOE OSTI2020

Metal–Organic Framework Nodes as a Supporting Platform for Tailoring the Activity of Metal Catalysts

Catalysis is a ubiquitous element of the modern economy, representing a cornerstone of many sectors including energy, materials, and pharmaceuticals. Within this realm, 80% of reactions are carried out by heterogeneous catalysts due to their advantageous physical and chemical characteristics. In some heterogeneous systems, the reaction rate can be optimized through rational catalyst design, in which support materials can be tailored structurally and stereoelectronically for targeted purposes to better facilitate the catalytic reaction. To this end, metal-organic frameworks (MOFs) have garnered recent attention due to their high porosity, crystallinity, and chemical tunability, which can be used to derive structure-activity relationships in the design of catalysts. In this Perspective, we survey examples of catalytically active guest metals on the inorganic nodes of MOFs. This is done with the intention of providing design guidelines for tailoring chemical reactivity and insights into the opportunities for future growth in this field. Strategies for rational design in MOF catalysis include electronic tuning of the metal node in the MOF support, installing promoter ions onto the node to effect the reactivity of grafted metals, modulation of the spatial environment around the transition metal using the metal node structure, and achieving site uniformity in supported catalysts. By highlighting these efforts, we seek to underscore the role of MOF nodes as nonspectator supports for catalytic metal complexes and provide future directions for rational catalyst design by tuning reactivity on these anchoring platforms.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Metal Chalcogenide Nanofilms: Platforms for Mechanistic Studies of Electrocatalysis

The systematic development of improved electrocatalysts requires strategies for preparing candidate materials as well-defined thin-film electrodes that are amenable to straightforward characterization of reaction mechanism and catalyst specific activity. While numerous thin film preparation methods are established for transition metals and metal alloys, few strategies exist for transition metal chalcogenides, despite growing recognition of their role as potent electrocatalysts. Herein we show that electrochemical atomic layer deposition (E-ALD) is a powerful tool for accessing well-defined metal chalcogenide electrocatalysts, by synthesizing, for the first time, crystalline conformal films of Co 9 S 8 , a promising earth-abundant oxygen reduction catalyst, with tunable nanoscale thickness. The as-prepared nanofilms display relatively high activity for the oxygen reduction reaction and provide a robust platform for detailed mechanistic investigations. Initial mechanistic studies reveal that oxygen reduction on Co 9 S 8 nanofilms proceeds via rate-limiting one-electron transfer to O 2 with a specific activity of 20.6 μA cm –2 at 600 mV vs RHE. This study opens the door to the systematic application of E-ALD to investigate chalcogenide electrocatalysts across the transition series.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Toward Spatial Control of Reaction Selectivity on Photocatalysts Using Area-Selective Atomic Layer Deposition on the Model Dual Site Electrocatalyst Platform

Photocatalytic water splitting is a promising route to low-cost, green H 2 . However, this approach is currently limited in its solar-to-hydrogen conversion efficiency. One major source of efficiency loss is attributed to the high rates of undesired side and back reactions, which are exacerbated by the proximity of neighboring oxidation and reduction sites. Nanoscopic oxide coatings have previously been used to selectively block undesired reactants from reaching active sites; however, a coating encapsulating the entire photocatalyst particle limits activity as it cannot facilitate both half-reactions. In this work, area selective atomic layer deposition (AS-ALD) was used to selectively deposit semipermeable TiO 2 films onto model metallic cocatalysts for enhancing reaction selectivity while maintaining a high overall activity. Pt and Au were used as exemplary reduction and oxidation cocatalyst sites, respectively, where Au was deactivated toward ALD growth through self-assembled thiol monolayers while TiO 2 was coated onto Pt sites. Electroanalytical measurements of monometallic thin film electrodes showed that the TiO 2 -encapsulated Pt effectively suppressed undesired H 2 oxidation and Fe(II)/Fe(III) redox reactions while still permitting the desired hydrogen evolution reaction (HER). A planar model photocatalyst platform containing patterned interdigitated arrays of Au and Pt microelectrodes was further assessed using scanning electrochemical microscopy (SECM), demonstrating the successful use of AS-ALD to enable local reaction selectivity in a dual-reaction-site (photo)electrocatalytic system. Finally, interdigitated microelectrodes having independent potential control were used to show that selectively deposited TiO 2 coatings can suppress the rate of back reactions on neighboring active sites by an order of magnitude compared with uncoated control samples.

08 HYDROGEN↗
DOE OSTI2015

Co-registered Topographical, Band Excitation Nanomechanical, and Mass Spectral Imaging Using a Combined Atomic Force Microscopy/Mass Spectrometry Platform

The advancement of a hybrid atomic force microscopy/mass spectrometry imaging platform demonstrating for the first time co-registered topographical, band excitation nanomechanical, and mass spectral imaging of a surface using a single instrument is reported. The mass spectrometry-based chemical imaging component of the system utilized nanothermal analysis probes for pyrolytic surface sampling followed by atmospheric pressure chemical ionization of the gas phase species produced with subsequent mass analysis. We discuss the basic instrumental setup and operation and the multimodal imaging capability and utility are demonstrated using a phase separated polystyrene/poly(2-vinylpyridine) polymer blend thin film. The topography and band excitation images showed that the valley and plateau regions of the thin film surface were comprised primarily of one of the two polymers in the blend with the mass spectral chemical image used to definitively identify the polymers at the different locations. Data point pixel size for the topography (390 nm x 390 nm), band excitation (781 nm x 781 nm), mass spectrometry (690 nm x 500 nm) images was comparable and submicrometer in all three cases, but the data voxel size for each of the three images was dramatically different. The topography image was uniquely a surface measurement, whereas the band excitation image included information from an estimated 10 nm deep into the sample and the mass spectral image from 110-140 nm in depth. Moreover, because of this dramatic sampling depth variance, some differences in the band excitation and mass spectrometry chemical images were observed and were interpreted to indicate the presence of a buried interface in the sample. The spatial resolution of the mass spectral image was estimated to be between 1.5 m 2.6 m, based on the ability to distinguish surface features in that image that were also observed in the other images.

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

A Hybrid Molecular–Nanophotonic Platform for On-Chip Cavity Quantum Electrodynamics and Collective Interactions

We present a hybrid solid-state cavity quantum electrodynamics (QED) platform that integrates a high density of coherent organic molecules with high-quality-factor nanophotonics. Thin anthracene crystals doped with dibenzoterrylene (DBT) are mechanically transferred onto prefabricated silicon nitride photonic crystal cavities, preserving both the cavity quality and molecular coherence. This approach decouples emitter synthesis from nanofabrication, providing a pathway for integrating other types of emitters. The high density of molecular emitters results in up to ten molecules being coupled to a single cavity. By tuning pairs of molecules into resonance within a single cavity mode, we observe cavity-mediated interactions in both dispersive and dissipative regimes. Furthermore, these results establish an accessible route to deterministic on-chip single- and multiphoton sources.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2020

Multiplex Evolution of Antibody Fragments Utilizing a Yeast Surface Display Platform

Advances in high-throughput synthetic biology technologies based on the CRISPR/Cas9 system have enabled a comprehensive assessment of mutations conferring desired phenotypes, as well as a better understanding of genotype-phenotype correlations in protein engineering. Engineering antibodies to enhance properties such as binding affinity and stability plays an essential role in therapeutic applications. Here we report a method, multiplex navigation of antibody structure (MINAS), that combines a CRISPR/Cas9-based trackable editing method and fluorescent-activated cell sorting (FACS) of yeast-displayed libraries. We designed mutations in all of the complementarity-determining and framework regions of a well-characterized scFv antibody and mapped the contribution of these regions to enhanced properties. We identified specific mutants that showed higher binding affinities up to 100-fold compared to the wild-type. This study expands the applicability of CRISPR/Cas9-based trackable protein engineering by combining it with a surface display platform.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Dynamic Multiplexed Control and Modeling of Optogenetic Systems Using the High-Throughput Optogenetic Platform, Lustro

The ability to control cellular processes using optogenetics is inducer-limited, with most optogenetic systems responding to blue light. To address this limitation, we leverage an integrated framework combining Lustro, a powerful high-throughput optogenetics platform, and machine learning tools to enable multiplexed control over blue light-sensitive optogenetic systems. Specifically, we identify light induction conditions for sequential activation as well as preferential activation and switching between pairs of light-sensitive split transcription factors in the budding yeast, Saccharomyces cerevisiae. We use the high-throughput data generated from Lustro to build a Bayesian optimization framework that incorporates data-driven learning, uncertainty quantification, and experimental design to enable the prediction of system behavior and the identification of optimal conditions for multiplexed control. This work lays the foundation for designing more advanced synthetic biological circuits incorporating optogenetics, where multiple circuit components can be controlled using designer light induction programs, with broad implications for biotechnology and bioengineering.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Nanoporous Gold as a Platform for a Building Block Catalyst

The porous bulk materials are of great interest in catalysis because they can be employed in heterogeneous gas and liquid phase catalysis, electrocatalysis, and in electrocatalytic sensing. Nanoporous gold gained considerable attraction in this context because it is the prime example of a corrosion-derived nanoporous bulk metal. Moreover, the material was shown to be a very active and selective Au type catalyst for a variety of oxidation reactions. In leveraging the functionalization of the surface of the material with various additives, its catalytic applications can be extended and tuned. In this review, we will summarize recent developments in using nanoporous gold as the platform for the development of high performance catalytic materials by adding metals, metal oxides, and molecular functionalities as building blocks.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Synthesis and Lanthanide Coordination Chemistry of Phosphine Oxide Decorated Dibenzothiophene and Dibenzothiophene Sulfone Platforms

Syntheses for new ligands based upon dibenzothiophene and dibenzothiophene sulfone platforms, decorated with phosphine oxide and methylphosphine oxide donor groups, are described. Coordination chem. of 4, 6- bis(diphenylphosphinoylmethyl) dibenzothiophene (8) , 4, 6- bis(diphenylphosphinoylmethyl) dibenzothiophene- 5, 5- dioxide (9) and 4, 6- bis(diphenylphosphinoyl) dibenzothiophene- 5, 5- dioxide (10) with lanthanide nitrates, Ln(NO3) 3 (H2O) n is outlined, and crystal structure detns. reveal a range of chelation interactions on Ln(III) ions. The HNO3 dependence of the solvent extn. performance of 9 and 10 in 1, 2- dichloroethane for Eu(III) and Am(III) is described and compared against the extn. behavior of related dibenzofuran ligands (2, 3; R = Ph) and n- octyl(phenyl) - N, N- diisobutylcarbamoylmethyl phosphine oxide (4) measured under identical conditions.

Rosario-Amorin, Daniel↗
DOE OSTI2021

A Tunable Multivariate Metal–Organic Framework as a Platform for Designing Photocatalysts

Catalysts for photochemical reactions underlie many foundations in our lives, from natural light harvesting to modern energy storage and conversion, including processes such as water photolysis by TiO 2 . Recently, metal–organic frameworks (MOFs) have attracted large interest within the chemical research community, as their structural variety and tunability yield advantages in designing photocatalysts to address energy and environmental challenges. Here, we report a series of novel multivariate metal–organic frameworks (MTV-MOFs), denoted as MTV-MIL-100. They are constructed by linking aromatic carboxylates and AB 2 OX 3 bimetallic clusters, which have ordered atomic arrangements. Synthesized through a solvent-assisted approach, these ordered and multivariate metal clusters offer an opportunity to enhance and fine-tune the electronic structures of the crystalline materials. Moreover, mass transport is improved by taking advantage of the high porosity of the MOF structure. Combining these key advantages, MTV-MIL-100(Ti,Co) exhibits a high photoactivity with a turnover frequency of 113.7 mol H2 gcat. –1 min –1 , a quantum efficiency of 4.25%, and a space time yield of 4.96 × 10 –5 in the photocatalytic hydrolysis of ammonia borane. Bridging the fields of perovskites and MOFs, this work provides a novel platform for the design of highly active photocatalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

An Enzymatic Platform for Primary Amination of 1-Aryl-2-alkyl Alkynes

Propargyl amines are versatile synthetic intermediates with numerous applications in the pharmaceutical industry. An attractive strategy for efficient preparation of these compounds is nitrene propargylic C(sp 3 )–H insertion. However, achieving this reaction with good chemo-, regio-, and enantioselective control has proven to be challenging. Here, we report an enzymatic platform for the enantioselective propargylic amination of alkynes using a hydroxylamine derivative as the nitrene precursor. Cytochrome P450 variant PA-G8 catalyzing this transformation was identified after eight rounds of directed evolution. A variety of 1-aryl-2-alkyl alkynes are accepted by PA G8, including those bearing heteroaromatic rings. This biocatalytic process is efficient and selective (up to 2610 total turnover number (TTN) and 96% ee) and can be performed on preparative scale.

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

Bioenabled Platform to Access Polyamides with Built-In Target Properties

The diversification of platform chemicals is key to today’s petroleum industry. Likewise, the flourishing of tomorrow’s biorefineries will rely on molecules with next-generation properties from biomass. Herein, we explore this opportunity with a novel approach to monomers with custom property enhancements. Cyclic diacids with alkyl and aromatic decorations were synthesized from muconic acid by Diels-Alder cycloaddition and copolymerized with hexamethylenediamine and adipic acid to yield polyamides with built-in hydrophobicity and flame retardancy. Testing shows a 70% reduction in water uptake and doubling of char production while largely retaining other key properties of the parent Nylon-6,6. In conclusion, the present approach can be generalized to access a wide range of performance-advantaged polyamides.

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

Cyclobutanedicarboxylate Metal–Organic Frameworks as a Platform for Dramatic Amplification of Pore Partition Effect

Ultrafine tuning of MOF structures at sub-angstrom or picometer levels can help improve separation selectivity for gases with subtle differences. However, for MOFs with large-enough pore size, the effect from ultrafine tuning on sorption can be muted. Here we show an integrative strategy that couples together extreme pore compression with ultrafine pore tuning. Furthermore, this strategy is made possible by unique combination of two features of the pacs platform (pacs = partitioned acs): multi-modular framework and exceptional tolerance towards isoreticular replacement. Specifically, we use one module (Ligand 1, L1) to shrink pore size to an extreme minimum on pacs. A compression ratio of about 30% was achieved (based on unit-cell c/a ratio) from prototypical 1,4-benzenedicarboxylate-pacs to trans-1,3-cyclobutanedicarboxylate-pacs. This is followed by using another module (Ligand 2, L2) for ultrafine pore tuning (< 3% compression). This L1-L2 strategy increases C 2 H 2 /CO 2 selectivity from 2.6 to 20.8 and gives rise to excellent experi-mental breakthrough performance. Being the shortest cyclic dicarboxylate that mimics para-benzene-based moieties us-ing bioisosteric (BIS) strategy on pacs, trans-1,3-cyclobutanedicarboxylate-based MOF chemistry offers new opportuni-ties in MOF chemistry.

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

Biosynthesis of Minimal C-Phycocyanin Chromophore Assemblies in E. coli Provides a Platform to Dissect Protein-Mediated Tuning of Exciton Transfer

Cyanobacteria are arguably among the most evolutionarily successful organisms on Earth, inhabiting a wide range of ocean, freshwater, soil, and even desert environments on every continent. The cyanobacterial phycobilisome consists of stacks of disk-like light-collecting moieties, allophycocyanin (APC) and phycocyanin (CPC), with covalently bound phycocyanobilin (PCB) pigments. The ways in which the energies of the specific chromophores in these complexes are tuned by the protein to achieve its highly efficient and directional energy transfer are not fully understood, as complex combinations of decay pathways are occurring simultaneously and competitively through this elaborate light-harvesting system. This makes it difficult to extract information about isolated protein-pigment interactions. We provide herein a description of a useful new experimental platform in which we have recombinantly expressed a fully functioning CPC complex and selectively created minimal chromophore sets to study their individual contributions to the overall CPC spectra. Structural and computational analysis of this protein system have provided a greater understanding of how the protein environment serves to alter the photophysics of each of these chromophores. Introduction of a quencher into various positions within CPC confirmed the ability of the protein environment to tune the directionality of energy transport in this assembly. Further mutational analysis suggested the roles of key amino acids surrounding the chromophores, showcasing the utility of heterologous expression techniques for understanding the effects of structure on EET mechanisms in the phycobilisome.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗