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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Potential dependent spectroelectrochemistry of electrofluorogenic dyes on indium–tin oxide

Indium-tin oxide (ITO) is used in a variety of applications due to its electrical conductivity and optical transparency. Moreover, ITO-coated glass is a common working electrode for spectroelectrochemistry. Thus, the ITO substrates should exhibit well-understood spectroscopic characteristics. Here, we report anomalous potential-dependent luminescence emission from three structurally dissimilar electrofluorogenic probe on ITO-coated glass. The three probes, flavin mononucleotide, resorufin, and Nile blue, show the expected fluorescence modulation between their oxidized, emissive forms and their reduced, nonfluorescent forms at low laser irradiance and/or high concentrations. However, at high irradiance and/or low concentration, the emission intensity increases at reducing potentials, contrary to expectations. In addition, a strong interplay between probe molecule concentration and laser irradiance is observed. We attribute the anomalous behavior to a combination of (1) irradiance-dependent ITO carrier dynamics, and (2) interaction of the fluorescent probe with ITO at reducing potentials resulting in a charge transfer state with altered emission behavior. Thus, the potential- and irradiance-dependent behavior of ITO and the resulting charge transfer state may not only interfere with the observation of potential-dependent fluorescence from redox probes but can completely reverse the polarity of the potential-dependent luminescence, especially at high irradiance and low concentration.

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

Challenges and Development of Tin-Based Anode with High Volumetric Capacity for Li-Ion Batteries

Abstract The ever-increasing energy density needs for the mass deployment of electric vehicles bring challenges to batteries. Graphitic carbon must be replaced with a higher-capacity material for any significant advancement in the energy storage capability. Sn-based materials are strong candidates as the anode for the next-generation lithium-ion batteries due to their higher volumetric capacity and relatively low working potential. However, the volume change of Sn upon the Li insertion and extraction process results in a rapid deterioration in the capacity on cycling. Substantial effort has been made in the development of Sn-based materials. A SnCo alloy has been used, but is not economically viable. To minimize the use of Co, a series of Sn–Fe–C, Sn y Fe, Sn–C composites with excellent capacity retention and rate capability has been investigated. They show the proof of principle that alloys can achieve Coulombic efficiency of over 99.95% after the first few cycles. However, the initial Coulombic efficiency needs improvement. The development and application of tin-based materials in LIBs also provide useful guidelines for sodium-ion batteries, potassium-ion batteries, magnesium-ion batteries and calcium-ion batteries. Graphic Abstract

25 ENERGY STORAGE↗
DOE OSTI2023

Improving the barrier properties of tin oxide in metal halide perovskite solar cells using ozone to enhance nucleation

Here we investigate tin oxide growth on fullerene (C 60 ) by atomic layer deposition (ALD) for C 60 /oxide bilayer electron selective contacts in P-I-N metal halide perovskite (MHP) solar cells. An in situ ozone functionalization step is incorporated in an ALD SnO x process to suppress sub-surface growth, leading to improved internal barrier performance of ALD SnO x thin films grown on fullerene surfaces. We show that this approach decreases the water-vapor transmission rate of C 60 /ALD SnO x barriers by an order of magnitude and improves the barrier properties against gas, solvent, and halide migration. Furthermore, ozone-treated SnO x barriers can narrow photovoltaic performance distribution without compromising efficiency. We demonstrate the universality of this approach in wide-, intermediate-, and low-gap perovskite systems and further show that enhancement of the ALD barrier layer is critical toward improving the yield of all-perovskite tandem solar cells. Two-terminal all-perovskite tandem solar cells incorporating ozone nucleation are reported at over 24% photovoltaic conversion efficiency.

14 SOLAR ENERGY↗
DOE OSTI2020

On the irreversible sodiation of tin disulfide

Tin disulfide is considered as a promising electrode material for sodium-ion batteries because of its two-dimensional layered structural characteristics allowing the intercalation of Na ions. Understanding the underlying reaction mechanisms and the decisive step of the reaction reversibility is critical for its applications. Herein, we investigate the sodiation and desodiation processes of SnS 2 by employing in situ transmission electron microscopy (TEM). After the initial intercalation reaction, a rock-salt Na y SnS 2 phase with disordering Na and Sn cations is observed, followed with a conversion reaction and an alloying reaction. Additionally, the disordering reaction occurs along <1-10> direction of pristine SnS 2 phase which is correlated with local bonding rearrangements induced by the exchange of Sn and Na cations. In-situ TEM studies and first-principles calculations indicate that the original 2D SnS 2 structure could not be recovered during desodiation. Instead, the disordered Na y SnS 2 phase is finally formed, which indicates that the irreversible disordering transition is the determining step of irreversible cycling. This work probes the structural evolution of sodiation, providing a fundamental understanding of the electrochemical properties of metal sulfides and inspiring rational designs of high performance electrodes for sodium-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2023

Influence of oxygen on the optical and electrical properties of magnetron-sputtered indium tin oxide thin films at ambient temperature

Indium Tin Oxide (ITO) thin films are commonly used as transparent conductive layers in the production of solar cells. ITO films are typically heat-treated at temperatures exceeding 200 °C after magnetron sputtering to optimize the physical, optical, and electrical characteristics for photovoltaic devices. Here, this high temperature heating procedure greatly limits the use of potential substrates, particularly those comprised of low-temperature-rated polymers. Herein, we examine the physical, optical, and electrical transport effects of oxygen:argon plasmas during radio frequency magnetron sputtering of ITO on glass and flexible polymer surfaces without subsequent heat treatment. ITO thin films were characterized via sheet resistance testing, UV-Vis spectroscopy, X-ray diffraction, and scanning electron microscopy imaging. Sheet resistance measurements revealed an increase in surface resistance with increasing oxygen concentration during sputtering. UV-Vis optical transmittance measurements demonstrated an improvement in optical transmittance with an increase in oxygen concentration reaching a maximum transmittance at an oxygen concentration of 1-2 %. Most importantly, it was discovered that producing bilayers of ITO with pure argon sputtered plasmas followed by oxygen:argon plasmas produced ITO thin films with suitable resistance and transmittance without the need for high temperature post annealing. These results highlight a methodology for the deposition of ITO thin films on temperature sensitive substrates for flexible photovoltaics and low-cost module production.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Indium Tin-Doped Oxide Interactions with Solvent Radiolysis Products

Transparent conductive oxides (TCOs), such as indium tin-doped oxide (ITO), are ubiquitous as components of electronics and are ideal electrode substrates for catalysis, energy transformation reactions, and energy storage applications. Recently, researchers have recognized their effectiveness as electrode materials for manipulating actinide oxidation states in solution. Despite their popularity as electrode materials, prior studies focused extensively on the direct radiolysis of TCO materials in air and rarely examined these effects within a solution, limiting our fundamental understanding of the interactions between solvent radiolysis products and these substrates in high radiation environments. Here, in this study, we characterize the effects of solvent radiolysis products—arising from the gamma irradiation of water, aqueous nitric acid solutions, and n-dodecane—on the composition, surface speciation, and band structure of ITO thin films on a glass substrate as a function of absorbed dose using UV-visible spectroscopy, scanning electron microscopy, photoelectrochemistry, and X-ray photoelectron spectroscopy. Our work demonstrates that mesoporous thin film electrodes of ITO exposed to gamma radiation in each solvent accumulate defects and exhibit solvent and dose dependent changes to their surface and interfacial properties. These electrodes maintain their electrochemical function and improve their photoelectrochemical performance up to at least 100 kGy of accumulated gamma dose, confirming their utility in solvents exposed to ionizing radiation fields.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Imaging Anisotropic Waveguide Exciton Polaritons in Tin Sulfide

In recent years, novel materials supporting in-plane anisotropic polaritons have attracted a great deal of research interest due to their capability of shaping nanoscale field distributions and controlling nanophotonic energy flows. Here we report a nano-optical imaging study of waveguide exciton polaritons (EPs) in tin sulfide (SnS) in the near-infrared (near-IR) region using scattering-type scanning near-field optical microscopy (s-SNOM). With s-SNOM, we mapped in real space the propagative EPs in SnS, which show sensitive dependence on the excitation energy and sample thickness. Moreover, we found that both the polariton wavelength and propagation length are anisotropic in the sample plane. In particular, in a narrow spectral range from 1.32 to 1.44 eV, the EPs demonstrate quasi-one-dimensional propagation, which is rarely seen in natural polaritonic materials. Here, a further analysis indicates that the observed polariton anisotropy originates from the different optical band gaps and exciton binding energies along the two principal crystal axes of SnS.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2021

Self-Anchored Platinum-Decorated Antimony-Doped-Tin Oxide as a Durable Oxygen Reduction Electrocatalyst

The lifetime of commercial Proton Exchange Membrane Fuel Cells (PEMFCs) is circumscribed by the insufficient durability of commercial catalysts. The use of metal oxide supports in place of carbon significantly increases electrocatalyst durability. Herein, following density functional theory (DFT) predictions of improved Platinum (Pt) stability on antimony doped tin oxide (ATO) supports, we synthesized ATO whose morphology and crystal structure was engineered using a Pt anchoring technique. X-ray photoelectron spectroscopy (XPS) indicated that the Pt anchor sites aided in the reduction of Pt precursors to Pt on the ATO surface. X-ray absorption near-edge spectroscopy (XANES) revealed the existence of strong-metal-support interactions (SMSI) between Pt and ATO. The combination of SMSI and high control over Pt dispersion enabled the Pt/Pt-aerogel-ATO (Pt supported on aerogel ATO with Pt anchor sites) electrocatalyst to achieve 2x the area specific activity of Pt/C in ex-situ testing. In a H 2 /air PEMFC Pt/Pt-aerogel-ATO cathodes enabled 20% higher peak power density and <1/6 the loss of active surface area as compared to Pt/C. Notably, in a PEMFC under rigorous potential cycling, the Pt/Pt-aerogel-ATO retained its initial peak power density as opposed to a 58% loss for Pt/C. Further, cost models indicate that Pt/Pt-aerogel-ATO is 26% less expensive than Pt/C over its useful lifetime.

25 ENERGY STORAGE↗
DOE OSTI2021

Atomically Dispersed Tin-Modified $\gamma$-alumina for Selective Propane Dehydrogenation under H 2 S Co-feed

Developing an earth-abundant catalyst that is sulfur-tolerant, active, and highly selective is of great interest for valorizing natural gas streams containing sour gas. Here, a tin-modified alumina catalyst is reported that is stable and selective for propane dehydrogenation in the presence of percent quantities of H 2 S in the feed. In particular, Sn/Al 2 O 3 –S catalysts with 1.5–5% Sn content exhibit 98% selectivity with up to 16% conversion at 560 °C during the fourth cycle. Experimental and computational characterization shows that the active sites are the defect tricoordinated Al atoms. H 2 S pretreatment further modifies a portion of these sites via exchanging a neighboring oxygen atom with sulfur, thereby rendering them more active and selective. At low loadings, Sn is atomically dispersed and selectively binds to hydroxyl groups or oxygen atoms on Al 2 O 3 . This prevents the formation of original (unmodified) defect sites on Al 2 O 3 and improves overall selectivity. The activity and selectivity of the catalyst are heavily dependent on the chemical potential of sulfur and hydrogen because they influence both the relative concentration of the two types of sites and the overall reaction mechanism. Finally, the catalyst can be regenerated fully under a pure H 2 S stream, thereby precluding treatment under oxygen, which can lead to sintering.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Electrochemical Behavior of Cerium at an Indium Tin-Doped Oxide Electrode in Acidic Media

The redox behavior and speciation of cerium at mesoporous thin films composed of nanoparticles of indium tin-doped oxide (nITO) electrodes were characterized in pH 4.8, 0.1 M acetate buffer and both 0.1 and 1 M HNO 3 using electrochemical techniques and X-ray photoelectron spectroscopy. Anodic deposition of ceria species from Ce(III) to the nITO electrode was achieved under all solvent conditions via spontaneous condensation of electrochemically generated ceric hydroxide species. In 1 M nitric acid, the rate of CeO 2 dissolution is on the same order as CeO 2 deposition, resulting in negligible amounts of CeO 2 electrodeposited at the nITO surface. The cathodic stripping of CeO 2 from the nITO substrate deposited in 0.1 M nitric acid or pH 4.8 acetate buffer follows a 2-step process where Ce(IV)-oxide is initially reduced to an unstable Ce(III)-oxide species that rapidly undergoes acid catalyzed dissolution to yield soluble Ce(III) (aq) . These findings provide a foundation for the pH and anodic potential controlled deposition of CeO 2 thin films to ITO substrates, which can aid in the development of materials composed of ceria. As a result, they can also be used to infer likely analogous actinide redox behavior and speciation at these electrodes.

Cerium↗
DOE OSTI2026

Nanocrystal-to-Ligand Interfacial Thermal Transport: Plasmonic Indium Tin Oxide to Perylene Diimide Adsorbates

The generation and dissipation of heat in nanocrystals upon optical excitation is a process which may either limit or enhance their performance in certain applications. Using transient absorption spectroscopy, we tracked the flow of heat from plasmonic tin-doped indium oxide (ITO) nanocrystals to surface adsorbed perylenediimide (PDI) molecules upon excitation of the ITO near-infrared plasmon resonance. Here, we rationalize the derivative line shapes observed in the transient absorption bleach features are the result of thermal transfer from the ITO core to surface ligands based on temperature-dependent static absorption studies of the PDI molecules adsorbed on plasmonic ITO. Through a series of pump power dependent measurements, we demonstrate that the PDI heating time is largely fluence independent at the powers measured, while the overall recovery time increases. Elucidating thermal transfer rates at the nanocrystal and organic ligand interface is key for applications such as plasmon mediated photocatalysis, where heating may obfuscate hot carrier transfer processes.

heat dissipation↗
DOE OSTI2020

Materials Data on Sc(TiN)9 by Materials Project

Sc(TiN)9 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Sc3+ is bonded to six N3- atoms to form ScN6 octahedra that share corners with six TiN5 square pyramids, edges with six TiN6 octahedra, and edges with six TiN5 square pyramids. There are two shorter (2.18 Å) and four longer (2.19 Å) Sc–N bond lengths. There are five inequivalent Ti+2.67+ sites. In the first Ti+2.67+ site, Ti+2.67+ is bonded to five N3- atoms to form TiN5 square pyramids that share corners with two equivalent ScN6 octahedra, corners with seven TiN5 square pyramids, an edgeedge with one ScN6 octahedra, edges with five TiN6 octahedra, and edges with two TiN5 square pyramids. The corner-sharing octahedra tilt angles range from 2–3°. There are a spread of Ti–N bond distances ranging from 2.06–2.13 Å. In the second Ti+2.67+ site, Ti+2.67+ is bonded to six N3- atoms to form TiN6 octahedra that share corners with three TiN6 octahedra, corners with three equivalent TiN5 square pyramids, edges with two equivalent ScN6 octahedra, edges with two TiN6 octahedra, and edges with eight TiN5 square pyramids. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Ti–N bond distances ranging from 2.11–2.19 Å. In the third Ti+2.67+ site, Ti+2.67+ is bonded to five N3- atoms to form TiN5 square pyramids that share corners with four TiN6 octahedra, corners with five TiN5 square pyramids, an edgeedge with one ScN6 octahedra, edges with three TiN6 octahedra, and edges with four TiN5 square pyramids. The corner-sharing octahedra tilt angles range from 1–5°. There are a spread of Ti–N bond distances ranging from 2.06–2.16 Å. In the fourth Ti+2.67+ site, Ti+2.67+ is bonded to five N3- atoms to form TiN5 square pyramids that share a cornercorner with one ScN6 octahedra, corners with eight TiN5 square pyramids, an edgeedge with one ScN6 octahedra, edges with four TiN6 octahedra, and edges with three TiN5 square pyramids. The corner-sharing octahedral tilt angles are 2°. There are a spread of Ti–N bond distances ranging from 2.07–2.14 Å. In the fifth Ti+2.67+ site, Ti+2.67+ is bonded to six N3- atoms to form TiN6 octahedra that share corners with four equivalent TiN6 octahedra, corners with two equivalent TiN5 square pyramids, edges with two equivalent ScN6 octahedra, edges with two equivalent TiN6 octahedra, and edges with eight TiN5 square pyramids. The corner-sharing octahedra tilt angles range from 2–3°. There are four shorter (2.13 Å) and two longer (2.14 Å) Ti–N bond lengths. There are five inequivalent N3- sites. In the first N3- site, N3- is bonded to one Sc3+ and five Ti+2.67+ atoms to form a mixture of corner and edge-sharing NScTi5 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the second N3- site, N3- is bonded to one Sc3+ and five Ti+2.67+ atoms to form NScTi5 octahedra that share corners with six NTi6 octahedra and edges with eleven NScTi5 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the third N3- site, N3- is bonded to six Ti+2.67+ atoms to form a mixture of corner and edge-sharing NTi6 octahedra. The corner-sharing octahedra tilt angles range from 2–4°. In the fourth N3- site, N3- is bonded to one Sc3+ and five Ti+2.67+ atoms to form a mixture of corner and edge-sharing NScTi5 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the fifth N3- site, N3- is bonded to six Ti+2.67+ atoms to form NTi6 octahedra that share corners with six NTi6 octahedra and edges with ten NScTi5 octahedra. The corner-sharing octahedra tilt angles range from 0–5°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TiN by Materials Project

TiN is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ti3+ is bonded to six equivalent N3- atoms to form a mixture of edge and corner-sharing TiN6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ti–N bond lengths are 2.13 Å. N3- is bonded to six equivalent Ti3+ atoms to form a mixture of edge and corner-sharing NTi6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TiN by Materials Project

TiN is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Ti3+ is bonded in a body-centered cubic geometry to eight equivalent N3- atoms. All Ti–N bond lengths are 2.29 Å. N3- is bonded in a body-centered cubic geometry to eight equivalent Ti3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TiN by Materials Project

TiN is Zincblende, Sphalerite structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Ti3+ is bonded to four equivalent N3- atoms to form corner-sharing TiN4 tetrahedra. All Ti–N bond lengths are 1.99 Å. N3- is bonded to four equivalent Ti3+ atoms to form corner-sharing NTi4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Parameterization of the β and γ phases of Tin using the Vinet and Mie-Grüneisen Equations of State

When testing new phase aware materials models, it is often not possible to use tabulated Equations of States for the phases since the model might only be available in a smaller specialized research code without capability to read in tables. These EOS parameterizations for two of the solid phases of Tin were developed for testing the Kinetic Phase Transition model by Carl Greeff, LANL. They are based on two isotherms per phase obtained from work in progress by Carl Greeff, and their phase boundary corresponds fairly well to SESAME 2162. A full machinery is applied for the parameterization of the Vinet EOSs while the Mie-Grüneisen parameterizations are translated from the Vinet EOSs.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Recent Developments of Tin (II) Sulfide/Carbon Composites for Achieving High-Performance Lithium Ion Batteries: A Critical Review

The ever-increasing worldwide energy demand and the limited resources of fossil have forced the urgent adoption of renewable energy sources. Additionally, concerns over CO 2 emissions and potential increases in fuel prices have boosted technical efforts to make hybrid and electric vehicles more accessible to the public. Rechargeable batteries are undoubtedly a key player in this regard, especially lithium ion batteries (LIBs), which have high power capacity, a fast charge/discharge rate, and good cycle stability, while their further energy density improvement has been severely limited, because of the relatively low theoretical capacity of the graphite anode material which is mostly used. Among various high-capacity anode candidates, tin (II) sulfide (SnS 2 ) has been attracted remarkable attention for high-energy LIBs due to its enormous resource and simplicity of synthesis, in addition to its high theoretical capacity. However, SnS 2 has poor intrinsic conductivity, a big volume transition, and a low initial Coulombic efficiency, resulting in a short lifespan. SnS 2 /carbon composites have been considered to be a most promising approach to addressing the abovementioned issues. Therefore, this review summarizes the current progress in the synthesis of SnS 2 /carbon anode materials and their Li-ion storage properties, with special attention to the developments in Li-based technology, attributed to its immense current importance and promising prospects. Finally, the existing challenges within this field are presented, and potential opportunities are discussed.

25 ENERGY STORAGE↗