3D CoSe@C Aerogel as a Host for Dendrite-Free Lithium-Metal Anode and Efficient Sulfur Cathode in Li–S Full Cells
Abstract not provided.
Chemistry↗
SEARCH · Engineering Papers
Results for “Nanowire”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Molten Salts-Driven Discovery of a Polar Mixed-Anion 3D Framework at the Nanoscale: Zn 4 Si 2 O 7 Cl 2 , Charge Transport and Photoelectrocatalytic Water Splitting
Mixed-anion compounds widen the chemical space of attainable materials compared to single anionic compounds, but the exploration of their structural diversity is limited by common synthetic paths. Especially, oxychlorides rely mainly on layered structures, which suffer from low stability during photo(electro)catalytic processes. Herein we report a strategy to design a new polar 3D tetrahedral framework with composition Zn 4 Si 2 O 7 Cl 2 . We use a molten salt medium to enable low temperature crystallization of nanowires of this new compound, by relying on tetrahedral building units present in the melt to build the connectivity of the oxychloride. These units are combined with silicon-based connectors from a non-oxidic Zintl phase to enable precise tuning of the oxygen content. This structure brings high chemical and thermal stability, as well as strongly anisotropic hole mobility along the polar axis. These features, associated with the ability to adjust the transport properties by doping, enable to tune water splitting properties for photoelectrocatalytic H 2 evolution and water oxidation. This work then paves the way to a new family of mixed-anion solids
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Electrolysis on a Chip with Tunable Thin Film Nanostructured PGM Electrocatalysts Generated from Self-Assembled Block Copolymer Templates
Self-assembled block copolymers are promising templates for fabricating thin film materials with tuned periodic feature sizes and geometry at the nanoscale. Here, a series of nanostructured platinum and iridium oxide electrocatalysts templated from poly(styrene)-block-poly(vinyl pyridine) (PSbPVP) block copolymers via an incipient wetness impregnation (IWI) pathway is reported. Both nanowire and nanocylinder electrocatalysts of varying feature sizes are assessed and higher catalyst loadings are achieved by the alkylation of the pyridine moieties in the PVP block prior to IWI. Electrocatalyst evaluations featuring hydrogen pump and water electrolysis demonstrations are carried out on interdigitated electrode (IDE) chips flexible with liquid supporting electrolytes and thin film polymer electrolytes. Notably, the mass activities of the nanostructured electrocatalysts from alkylated block copolymer templates are 35%–94% higher than electrocatalysts from non-alkylated block copolymer templates. Standing cylinder nanostructures lead to higher mass activities than lamellar variants despite their not having the largest surface area per unit catalyst loading demonstrating that mesostructure architectures have a profound impact on reactivity. Overall, IDE chips with model thin film electrocatalysts prepared from self-assembled block copolymers offer a high-throughput experimental method for correlating electrocatalyst nanostructure and composition to electrochemical reactivity.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Single‐Atomic Site Catalyst with Heme Enzymes‐Like Active Sites for Electrochemical Sensing of Hydrogen Peroxide
Abstract Heme enzymes, with the pentacoordinate heme iron active sites, possess high catalytic activity and selectivity in biosensing applications. However, they are still subject to limited catalytic stability in the complex environment and high cost for broad applications in electrochemical sensing. It is meaningful to develop a novel substitute that has a similar structure to some heme enzymes and mimics their enzyme activities. One emerging strategy is to design the Fe‐N‐C based single‐atomic site catalysts (SASCs). The obtained atomically dispersed Fe‐N x active sites can mimic the active sites of heme enzymes effectively. In this work, a SASC (Fe‐SASC/NW) is synthesized by doping single iron atoms in polypyrrole (PPy) derived carbon nanowire via a zinc‐atom‐assisted method. The proposed Fe‐SASC/NW shows high heme enzyme‐like catalytic performance for hydrogen peroxide (H 2 O 2 ) with a specific activity of 42.8 U mg −1 . An electrochemical sensor based on Fe‐SASC/NW is developed for the detection of H 2 O 2 . This sensor exhibits a wide detection concentration range from 5.0 × 10 −10 m to 0.5 m and an excellent limit of detection (LOD) of 46.35 × 10 −9 m . Such excellent catalytic activity and electrochemical sensing sensitivity are attributed to the isolated Fe‐N x active sites and their structural similarity with natural metalloproteases.
Ding, Shichao↗
Tip-Induced 3D Printing on the Nanoscale with Field Emission Scanning Probes
3D printing down to the nanoscale remains a significant challenge. In this paper, the study explores the use of scanning probes that emit low-energy electrons (<100 eV) coupled with the localized injection and electron-induced decomposition of precursor molecules, for the precise localized deposition of 3D nanostructures. The experiments are performed inside the chamber of a scanning electron microscope (SEM), enabling the use of the in-built gas injector system (GIS) with gaseous naphthalene precursor for carbon deposition, as well as immediate inspection of the deposits by SEM. Substrate materials are planar fused silica with thin conductive coatings and non-planar copper wedges. After investigation of the deposition process parameters, various 2D and 3D carbon deposits are grown. Vertical nanowires several microns in length with a diameter <100 nm are achieved and 3D deposits with a high degree of nanoscale branching are also obtained, presumably due to a charging effect. High aspect ratio carbon nanostructures such as those demonstrated here can be employed as miniaturized electrodes or field emitters. The tip-based approach presented thus paves the way toward 3D nanoscale printing of various materials and functional nanostructures.
3D printing↗
Tailoring the d-band center on Ru 1 Cu single-atom alloy nanotubes for boosting electrochemical non-enzymatic glucose sensing
The development of cost-effective and highly efficient electrocatalysts is critical to help electrochemical non-enzymatic sensors achieve high performance. Here, in this work, a new class of catalyst, Ru single atoms confined on Cu nanotubes as a single-atom alloy (Ru 1 Cu NTs), with a unique electronic structure and property, was developed to construct a novel electrochemical non-enzymatic glucose sensor for the first time. The Ru 1 Cu NTs with a diameter of about 24.0 nm showed a much lower oxidation potential (0.38 V) and 9.0-fold higher response (66.5 μA) current than Cu nanowires (Cu NWs, oxidation potential 0.47 V and current 7.4 μA) for glucose electrocatalysis. Moreover, as an electrochemical non-enzymatic glucose sensor, Ru1Cu NTs not only exhibited twofold higher sensitivity (54.9 μA mM −1 cm −2 ) and wider linear range (0.5–8 mM) than Cu NWs, but also showed a low detection limit (5.0 μM), excellent selectivity, and great stability. According to theoretical calculation results, the outstanding catalytic and sensing performance of Ru 1 Cu NTs could be ascribed to the upshift of the d-band center that helped promote glucose adsorption. This work presents a new avenue for developing highly active catalysts for electrochemical non-enzymatic sensors.
electrochemistry↗
The heterogeneous nature of mechanically accelerated grain growth
Abstract While grain growth is traditionally viewed as a purely thermally driven process, nanocrystalline metals can undergo grain growth under mechanical loads, even at room temperature. We performed a detailed atomistic study of the heterogeneous nature of mechanically accelerated grain growth in a polycrystalline Pt nanowire. Using molecular dynamics simulations, we compared the grain-growth behavior of individual grains during tensile and shear cyclic loading, for three different equivalent strain levels, and at two temperatures. Pure thermal grain growth with no mechanical loading provided a baseline reference case. On average, grains that were already susceptible to thermal grain growth were stimulated to grow faster with mechanical loading, as expected. However, when analyzed on a grain-by-grain basis, the results were far more complex: grains that grew fastest under one stimuli were less accelerated under other stimuli. Even when the magnitude of loading changed, the relative growth of individual grains was distorted. We interpret this complexity from the perspective of superimposed growth mechanisms.
Chen, Elton Y.↗
Atomic Layer Deposition Niobium Nitride Films for High-Q Resonators
Niobium nitride (NbN) is a useful material for fabricating detectors because of its high critical temperature and relatively high kinetic inductance. In particular, NbN can be used to fabricate nanowire detectors and mm-wave transmission lines. When deposited, NbN is usually sputtered, leaving room for concern about uniformity at small thicknesses. In this work, we present atomic layer deposition niobium nitride (ALD NbN) as an alternative technique that allows for precision control of deposition parameters such as film thickness, stage temperature, and nitrogen composition. Atomic-scale control over film thickness admits a high degree of uniformity for films 4–30 nm thick; control over deposition temperature gives rise to growth rate changes, which can be used to optimize film thickness and critical temperature. In order to charac- terize ALD NbN in the radio-frequency regime, we construct single-layer micro- wave resonators and test their performance as a function of stage temperature and input power. ALD processes can admit high resonator quality factors, with ≥ 43% of resonators above Q i = 10 6 , which in turn increase detector multiplexing capabilities. i Furthermore, we find critical temperatures in the range of 7.5–10.9 K that vary as a function of cycle count and deposition temperature.
79 ASTRONOMY AND ASTROPHYSICS↗
Nanoarray-Based Monolithic Adsorbers for SO 2 Removal
Nanoarray-based monolithic catalysts have been developed for various applications, including CO oxidation, hydrocarbon combustion, lean NO x trapping, and low-pressure CO 2 hydrogenation. In this work, SO 2 adsorption properties have been explored and evaluated on the cordierite honeycomb monoliths grown with zinc oxide nanoarray (ZnO), zinc oxide nanoarray washcoated by BaCO 3 nanoparticles (ZnO/BaCO 3 ), and manganese oxide nanowire array with cryptomelane structure (MnO x ) at a temperature range from 50 to 425 °C. All samples show temperature-dependent SO 2 adsorption behaviors. The adsorption results reveal the performance order: MnO x > ZnO/BaCO 3 > ZnO, with ~ 90% SO 2 adsorbed in MnO x at 425 °C. Washcoated BaCO 3 contributes to the improvement of SO 2 adsorption in ZnO nanoarray, and the best performance displayed in MnO x may be attributed to their high specific surface area. After regeneration, nanoarrays all exhibit good thermal stability during test-regeneration cycles. No additional phase is formed in regenerated ZnO nanoarrays (ZnO-R), while BaCO 3 is converted to BaSO 4 in the regenerated ZnO/BaCO 3 nanoarrays (ZnO/BaCO 3 -R), and the sulfur species (possibly MnSO 4 ) and Mn 2 O 3 are found in regenerated MnO x nanoarrays (MnO x -R). It is noted that a small amount of sulfur species (possibly MnSO 4 ) may promote the SO 2 adsorption of MnO x -R at a lower temperature, while the formed Mn 2 O 3 contributes to the deactivation of MnO x -R.
36 MATERIALS SCIENCE↗
High Speed In-situ X-ray Imaging of 3D Freeze Printing of Aerogels
3D freeze printing (3DFP) combines drop-on-demand (DOD) inkjet printing with freeze casting to fabricate lightweight and multifunctional aerogels with customized geometries. Freeze casting is an efficient and easily implemented method capable of fabricating porous, sponge-like structures for many different applications. This process enables tailoring the microstructure of the final product (i.e., pore morphology, alignment, average size distribution, etc.) by controlling the fabrication conditions and freezing kinetics. Furthermore, its combination with DOD printing provides the capability of engineering the macrostructure without relying on a mold as reported for 3D freeze-printed aerogels made from graphene, silver nanowires, and other nanocomposites. In this paper, we performed in-situ X-ray imaging to understand the inside process dynamics in 3DFP using a commercially available colloidal silica ink. We investigated the 3DFP process with the following hierarchy: first, single droplets; then, uniform lines obtained from coalescence of droplets; and finally, three consecutive lines deposited layer by layer. With the help of X-ray imaging, the importance of the balance between material deposition and freezing rates was shown in-situ by the observation inside of the freeze front following the tip of the printed line. The effects of the substrate temperature on the elimination of undesired interfacial boundaries were also shown by the observed ice crystals penetrating from lower to upper layer.
36 MATERIALS SCIENCE↗
TiO x -supported Na-Mn-W oxides for the oxidative coupling of methane
Supported Na-Mn-W oxides are among the most studied catalysts for the oxidative coupling of methane (OCM) because of their superior thermal stability and relatively high C 2+ product yields. However, because of the structural complexity, the roles of each component in these catalysts have been controversial. In this work, WO x and MnO x sites were supported on titanate nanowires and employed in OCM studies. Compared to the commonly studied silica support, which is subject to severe restructuring due to the Na-induced crystallization, titanate support not only serves as a reservoir for alkali metals (e.g., Na), but also stabilizes isolated MnO x species. The catalytic performance of the titanate-based catalyst is similar to that of reference catalyst, MnO x /Na 2 WO 4 /SiO 2 , with a synergistic effect between MnO x and WO x sites. Further, advanced electron microscopy, X-ray diffraction, infrared spectroscopy, and X-ray absorption near edge structure spectroscopy suggest that the basic NaO x and MnO x species have strong interactions with the acidic WO x and TiO x species, which might contribute to the high selectivity toward C 2+ products and suppressed CO x formation.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
High performance Nb/TiNi nanocomposites produced by packaged accumulative roll bonding
Taking full advantage of intrinsic high strength of nano-reinforcements has been proven difficult in a composite until the concept of strain matching was experimental verified in a nanowire Nb/TiNi in-situ composite, which was obtained via solidifying eutectic Nb/TiNi and subsequent severe wire drawing. However, the volume fraction of the nano-reinforcement was dictated by eutectic reaction, which severely limited the development of high-performance composites. Here, the martensitic transformation nanocomposites were successfully acquired with increased volume fraction and changeable morphology of the nano-reinforcement through hot packaged ARB (PARB) and subsequent wire drawing. The nano-reinforcement with lamellar configuration in the composite could exhibit a large lattice strain of similar to 3.8%, which demonstrated the applicability and effectiveness of the strain matching principle in nano-lamellar composite. The obtained composites show a yield strength over 2.0 GPa and a quasi-linear elastic strain as larger as similar to 6.5% with adjustable apparent elastic modulus from 30 to 50 GPa.
42 ENGINEERING↗
High-throughput characterization of Ag–V–O nanostructured thin-film materials libraries for photoelectrochemical solar water splitting
Ag–V–O thin-film materials libraries, with both composition (Ag 22-77 V 23-78 O x ) and thickness (123–714 nm) gradients were fabricated using combinatorial reactive magnetron co-sputtering aiming on establishing relations between composition, structure, and functional properties. As-deposited libraries were annealed in air at 300 °C for 10 h. High-throughput characterization methods of composition, structure and functional properties were used to identify photoelectrochemically active regions. The phases AgV 6 O 15 , Ag 2 V 4 O 11 , AgVO 3 , and Ag 4 V 2 O 7 were observed throughout the composition gradient. The photoelectrochemical properties of Ag–V–O films are dependent on composition and morphology. An enhanced photocurrent density (~300–554 μA/cm 2 ) was obtained at 30 to 45 at.% Ag along the thickness gradient. Thin films of these compositions show a nanowire morphology, which is an important factor for the enhancement of photoelectrochemical performance. The photoelectrochemically active regions were further investigated by high-throughput synchrotron-X-ray diffraction and transmission electron microscopy (Ag 32 V 68 O x ) which confirmed the presence of Ag 2 V 4 O 11 as the dominating phase along with the minor phases AgV 6 O 15 and AgVO 3 . This enhanced photoactive region shows bandgap values of ~2.30 eV for the direct and ~1.87 eV for the indirect bandgap energies. Finally, the porous nanostructured films improve charge transport and are hence of interest for photoelectrochemical water splitting.
36 MATERIALS SCIENCE↗
Macro copper-graphene composites with enhanced electrical conductivity
Composites demonstrating simultaneously enhanced-electrical conductivity, current density and lowered-temperature coefficient of resistance (TCR) compared to copper have been highly sought after for their advantages in efficient energy transport behavior. While such conductors have been demonstrated in 1D (nanowires) and 2D (films) samples, achieving similar behavior in 3D has been challenging owing to the limitations of the synthesis techniques used. In this paper, novel macro-scale 3D copper conductors were demonstrated with simultaneously increased electrical conductivity and decreased temperature coefficient of resistance (TCR) through the addition of graphene. Hot-extrusion was used to manufacture over 1-m-long, 2-mm-diameter copper-graphene composites with varying graphene content and defect density. Results showed that the electrical conductivity and current density in composites with low defect density graphene increased monotonically as a function of graphene content. They also demonstrated a significant decrease of over 17% in TCR with the addition of only 15 ppm graphene along with over 52% improvement in current density. Comparatively composites with high defect density graphene demonstrated lower electrical conductivity and current density. This study provides first-of-its-kind evidence of 3D metal composites whose bulk electrical performance has been enhanced using graphene additive in minute quantities. Further developments in this area are essential to achieve high performance composite conductors that can improve energy transport efficiency and pave way for industrial adoption of such materials in the future.
36 MATERIALS SCIENCE↗
Operando Revealing Dynamic Reconstruction of NiCo Carbonate Hydroxide for High-Rate Energy Storage
Transition metal carbonate hydroxide (CH) has been widely explored as a promising battery-type electrode for high-rate energy storage. However, its genuine active sites under realistic operating conditions remains elusive. In this work, by virtue of the cutting-edge operando X-ray absorption spectroscopy, we unfold the dynamic evolution of the local electronic and geometric structures for the CH electrode upon cycling. Our results reveal that the irreversible redox of Co cations at the early stage of cyclic voltammetry (CV) cycling induces a phase transition in the NiCo CH nanowires forming oxygen vacancies-enriched NiCo layered double hydroxide (LDH) nanosheets with superior high-rate energy storage ability. Theoretical modeling demonstrates that the unsaturated 5-coordinated Co sites exhibit optimal redox reaction energy barrier and immensely promote the performance. These findings not only elucidate the electrochemical susceptibility of the Co-based carbonate hydroxide under operando conditions, but also highlight an electrochemical coordination-engineering strategy for the rational design of high-performance electrode.
25 ENERGY STORAGE↗
Battery anode design: From 1D nanostructure to 3D nanoarchitecture – Enabling next-generation energy storage technology
Recently, many studies have reported the efficacy of 1D silicon nanostructures as anode materials (mostly nanowires) due to their large surface to volume ratio which could be an advantage in terms of charging kinetics. Anode design is a crucial factor for the further development of lithium-ion battery (LIB) technology, especially in terms of achieving the high charging rate performance, as typically needed in electric vehicles (EV). 3D nanostructures have been identified as the key to dramatically enhanced charging rate of LIB, in addition to the change of materials (from carbon-based anode to silicon-based). However, existing fabrication methodologies for 3D nanostructures are inherently expensive – using advanced lithography techniques or other nanopatterning methodologies, as well as using additive manufacturing approaches. Electrospinning (as an integrated additive manufacturing methodology) may be used to produce low-cost 3D-printed fiber structures. Here, in the present study, we demonstrate the groundwork in this field of research in the past 3–4 years, which would allow the extension of this special additive manufacturing approach to reach nanoscale 3D-printed fiber structures more economically and with scalability for manufacturing. This would pave the way to achieve the order of magnitude increase in battery charging rate as needed to realize the vision of the electrification of mobility/transportation.
25 ENERGY STORAGE↗
Differential electron yield imaging with STXM
In this report total electron yield (TEY) imaging is an established scanning transmission X-ray microscopy (STXM) technique that gives varying contrast based on a sample's geometry, elemental composition, and electrical conductivity. However, the TEY-STXM signal is determined solely by the electrons that the beam ejects from the sample. A related technique, X-ray beam-induced current (XBIC) imaging, is sensitive to electrons and holes independently, but requires electric fields in the sample. Here we report that multi-electrode devices can be wired to produce differential electron yield (DEY) contrast, which is also independently sensitive to electrons and holes, but does not require an electric field. Depending on whether the region illuminated by the focused STXM beam is better connected to one electrode or another, the DEY-TXM contrast changes sign. DEY-STXM images thus provide a vivid map of a device's connectivity landscape, which can be key to understanding device function and failure. To demonstrate an application in the area of failure analysis, we image a 100 nm, lithographically-defined aluminum nanowire that has failed after being stressed with a large current density.
47 OTHER INSTRUMENTATION↗
Automated Crystal Orientation Mapping in py4DSTEM using Sparse Correlation Matching
Crystalline materials used in technological applications are often complex assemblies composed of multiple phases and differently oriented grains. Robust identification of the phases and orientation relationships from these samples is crucial, but the information extracted from the diffraction condition probed by an electron beam is often incomplete. We have developed an automated crystal orientation mapping (ACOM) procedure which uses a converged electron probe to collect diffraction patterns from multiple locations across a complex sample. We provide an algorithm to determine the orientation of each diffraction pattern based on a fast sparse correlation method. We demonstrate the speed and accuracy of our method by indexing diffraction patterns generated using both kinematical and dynamical simulations. We have also measured orientation maps from an experimental dataset consisting of a complex polycrystalline twisted helical AuAgPd nanowire. From these maps we identify twin planes between adjacent grains, which may be responsible for the twisted helical structure. All of our methods are made freely available as open source code, including tutorials which can be easily adapted to perform ACOM measurements on diffraction pattern datasets.
36 MATERIALS SCIENCE↗