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5. Bulk metallic glass-like structure of small icosahedral metallic nanoparticles

Author

Doan-Nguyen, Vicky V. T., Kimber, Simon A. J., Pontoni, Diego, Diroll, Benjamin T., Reifsnyder, Danielle C., Miglierini, Marcel, Yang, Xiaohao, Murray, Christopher B., and Billinge, Simon J. L.

Subjects
Condensed Matter - Materials Science
Abstract

We demonstrate a remarkable equivalence in structure measured by total X-ray scattering methods between very small metallic nanoparticles and bulk metallic glasses (BMGs), thus connecting two disparate fields, shedding new light on both. Our results show that for nanoparticle diameters <5 nm the structure of Ni nanoparticles changes from fcc to the characteristic BMG-like structure, despite them being formed from a single element, an effect we call nano-metallic glass (NMG) formation. However, high-resolution TEM images of the NMG clusters exhibit lattice fringes indicating a locally well-ordered, rather than glassy, structure. These seemingly contradictory results may be reconciled by finding a locally ordered structure that is highly isotropic and we show that local icosahedral packing within 5 atomic shells explains this. Since this structure is stabilized only in the vicinity of a surface which highlights the importance of the presence of free volume in BMGs for stabilizing similar local clusters., Comment: 14 pages, 5 figures

Published
2013
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6. Engineering titania nanostructure to tune and improve its photocatalytic activity

Author

Cargnello, Matteo, Montini, Tiziano, Smolin, Sergey Y., Priebe, Jacqueline B., Jaén, Juan J. Delgado, Doan-Nguyen, Vicky V. T., McKay, Ian S., Schwalbe, Jay A., Pohl, Marga-Martina, Gordon, Thomas R., Lu, Yupeng, Baxter, Jason B., Brückner, Angelika, Fornasiero, Paolo, and Murray, Christopher B.

Published
2016

9. Operando Studies Reveal Structural Evolution with Electrochemical Cycling in Li–CoS2

Author

Butala, Megan M., primary, Doan-Nguyen, Vicky V. T., additional, Lehner, Anna J., additional, Göbel, Claudia, additional, Lumley, Margaret A., additional, Arnon, Shiri, additional, Wiaderek, Kamila M., additional, Borkiewicz, Olaf J., additional, Chapman, Karena W., additional, Chupas, Peter J., additional, Balasubramanian, Mahalingam, additional, and Seshadri, Ram, additional

Published
2018
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10. Sodium Vanadium Fluorophosphates (NVOPF) Array Cathode Designed for High‐Rate Full Sodium Ion Storage Device

Author

Chao, Dongliang, primary, Lai, Chun‐Han (Matt), additional, Liang, Pei, additional, Wei, Qiulong, additional, Wang, Yue‐Sheng, additional, Zhu, Changrong (Rose), additional, Deng, Gang, additional, Doan‐Nguyen, Vicky V. T., additional, Lin, Jianyi, additional, Mai, Liqiang, additional, Fan, Hong Jin, additional, Dunn, Bruce, additional, and Shen, Ze Xiang, additional

Published
2018
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11. Chalcogels as electrode materials for Li-ion batteries

Author

Doan-Nguyen, Vicky V. T., primary, Subrahmanyam, Kota S., additional, Butala, Megan M., additional, Gerbec, Jeffrey A., additional, Islam, Saiful M., additional, Kanipe, Katherine N., additional, Wilson, Catrina E., additional, Balasubramanian, Mahalingam, additional, Wiaderek, Kamila M., additional, Borkiewicz, Olaf J., additional, Chapman, Karena W., additional, Chupas, Peter J., additional, Moskovits, Martin, additional, Dunn, Bruce S., additional, Kanatzidis, Mercouri G., additional, and Seshadri, Ram, additional

Published
2017
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12. Local Structure Evolution and Modes of Charge Storage in Secondary Li–FeS2 Cells

Author

Butala, Megan M., primary, Mayo, Martin, additional, Doan-Nguyen, Vicky V. T., additional, Lumley, Margaret A., additional, Göbel, Claudia, additional, Wiaderek, Kamila M., additional, Borkiewicz, Olaf J., additional, Chapman, Karena W., additional, Chupas, Peter J., additional, Balasubramanian, Mahalingam, additional, Laurita, Geneva, additional, Britto, Sylvia, additional, Morris, Andrew J., additional, Grey, Clare P., additional, and Seshadri, Ram, additional

Published
2017
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15. Molybdenum Polysulfide Chalcogels as High-Capacity, Anion-Redox-Driven Electrode Materials for Li-Ion Batteries

Author

Doan-Nguyen, Vicky V. T., Subrahmanyam, Kota S., Butala, Megan M., Gerbec, Jeffrey A., Islam, Saiful M., Kanipe, Katherine N., Wilson, Catrina E., Balasubramanian, Mahalingam, Wiaderek, Kamila M., Borkiewicz, Olaf J., Chapman, Karena W., Chupas, Peter J., Moskovits, Martin, Dunn, Bruce S., Kanatzidis, Mercouri G., and Seshadri, Ram

Abstract

Sulfur cathodes in conversion reaction batteries offer high gravimetric capacity but suffer from parasitic polysulfide shuttling. We demonstrate here that transition metal chalcogels of approximate formula MoS3.4achieve a high gravimetric capacity close to 600 mAh g–1(close to 1000 mAh g–1on a sulfur basis) as electrode materials for lithium-ion batteries. Transition metal chalcogels are amorphous and comprise polysulfide chains connected by inorganic linkers. The linkers appear to act as a “glue” in the electrode to prevent polysulfide shuttling. The Mo chalcogels function as electrodes in carbonate- and ether-based electrolytes, which further provides evidence of polysulfide solubility not being a limiting issue. We employ X-ray spectroscopy and operandopair distribution function techniques to elucidate the structural evolution of the electrode. Raman and X-ray photoelectron spectroscopy track the chemical moieties that arise during the anion-redox-driven processes. We find the redox state of Mo remains unchanged across the electrochemical cycling and, correspondingly, the redox is anion-driven.

Published
2024
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25. High-rate capability of Na2FePO4F nanoparticles by enhancing surface carbon functionality for Na-ion batteries.

Author

Ko, Jesse S., Doan-Nguyen, Vicky v. T., Kim, Hyung-Seok, Petrissans, Xavier, Deblock, Ryan H., Choi, Christopher S., Long, Jeffrey W., and Dunn, Bruce S.

Abstract

Metal phosphate compounds are considered promising candidates as positive electrode materials for Na-ion batteries because they offer higher cation-insertion potentials than analogous metal oxides. One such example is sodium iron fluorophosphate (Na2FePO4F), a compound that is typically synthesized by high-temperature solid-state routes. In this study, we prepare phase-pure Na2FePO4F using the polyol route, a low-temperature process that allows for the synthesis of nanoparticles (15–25 nm), a form that enhances Na-ion insertion kinetics and cycling stability. We then apply two methods to enhance the electronic conductivity of Na2FePO4F: (i) converting residual organic byproducts of the polyol synthesis to conductive carbon coatings; and (ii) preparing a nanocomposite with reduced graphene oxide. The resulting electrode materials are characterized in nonaqueous Na-ion electrolytes, assessing such metrics as specific capacity, rate capability, and cycling stability. A thorough electrochemical kinetics analysis is performed to deconvolve surface-vs.-bulk Na-ion insertion as a function of composite structure. Specific capacities between 60–110 mA h g−1 were achieved in galvanostatic charge–discharge tests when cycling in the range from 10C to C/10, respectively. [ABSTRACT FROM AUTHOR]

Published
2017
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30. Engineering uniform nanocrystals: Mechanism of formation and self-assembly into bimetallic nanocrystal superlattices.

Author

Cargnello, Matteo, Doan‐Nguyen, Vicky V. T., and Murray, Christopher B.

Subjects
NANOCRYSTALS, SUPERLATTICES, PARTICLE size distribution, CRYSTAL lattices, CATALYSIS
Abstract

The preparation of metal nanocrystals (NCs) with precise and tunable size is of great interest for many applications. Following previous reports on the synthesis of monodisperse nickel, palladium, and platinum NCs, we here show that the narrow size distributions are the result of an optimized combination of surfactants that play a dynamic, synergistic role in stabilizing the particles at different stages (nucleation, growth) of their preparation. This dynamical process allows the temporal separation of nucleation and growth responsible for the narrow size distributions achievable with this heat-up method. Finally, the uniform NCs are exploited in the preparation of binary nanocrystals superlattices entirely based on metal components, with promising applicability in the fields of catalysis, sensing, and optics. © 2015 American Institute of Chemical Engineers AIChE J, 62: 392-398, 2016 [ABSTRACT FROM AUTHOR]

Published
2016
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31. Na2Ti3O7Nanoplatelets and Nanosheets Derived from a Modified Exfoliation Process for Use as a High-Capacity Sodium-Ion Negative Electrode

Author

Ko, Jesse S., Doan-Nguyen, Vicky V. T., Kim, Hyung-Seok, Muller, Guillaume A., Serino, Andrew C., Weiss, Paul S., and Dunn, Bruce S.

Abstract

The increasing interest in Na-ion batteries (NIBs) can be traced to sodium abundance, its low cost compared to lithium, and its intercalation chemistry being similar to that of lithium. We report that the electrochemical properties of a promising negative electrode material, Na2Ti3O7, are improved by exfoliating its layered structure and forming 2D nanoscale morphologies, nanoplatelets, and nanosheets. Exfoliation of Na2Ti3O7was carried out by controlling the amount of proton exchange for Na+and then proceeding with the intercalation of larger cations such as methylammonium and propylammonium. An optimized mixture of nanoplatelets and nanosheets exhibited the best electrochemical performance in terms of high capacities in the range of 100–150 mA h g–1at high rates with stable cycling over several hundred cycles. These properties far exceed those of the corresponding bulk material, which is characterized by slow charge-storage kinetics and poor long-term stability. The results reported in this study demonstrate that charge-storage processes directed at 2D morphologies of surfaces and few layers of sheets are an exciting direction for improving the energy and power density of electrode materials for NIBs.

Published
2017
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33. Ligand Coupling Symmetry Correlates with Thermopower Enhancement in Small-Molecule/Nanocrystal Hybrid Materials

Author

Lynch, Jared, Kotiuga, Michele, Doan-Nguyen, Vicky V. T., Queen, Wendy L., Forster, Jason D., Schlitz, Ruth A., Murray, Christopher B., Neaton, Jeffrey B., Chabinyc, Michael L., and Urban, Jeffrey J.

Subjects
quantum dot thermoelec inorg org composite ligand coupling symmetry
Abstract

The authors study the impact of the coupling symmetry and chem. nature of org.-inorg. interfaces on thermoelec. transport in Cu2-xSe nanocrystal thin films. By coupling ligand-exchange techniques with layer-by-layer assembly methods, the authors are able to systematically vary nanocrystal-org. linker interfaces, demonstrating how the functionality of the polar headgroup and the coupling symmetry of the org. linkers can change the power factor (S2σ) by nearly 2 orders of magnitude. Remarkably, ligand-coupling symmetry has a profound effect on thermoelec. transport in these hybrid materials. The authors shed light on these results using intuition from a simplified model for interparticle charge transport via tunneling through the frontier orbital of a bound ligand. The authors' anal. indicates that ligand-coupling symmetry and binding mechanisms correlate with enhanced cond. approaching 2000 S/cm, and the authors employ this concept to demonstrate among the highest power factors measured for quantum-dot based thermoelec. inorg.-org. composite materials of ∼30 μW/m·K2.

34. Engineering titania nanostructure to tune and improve its photocatalytic activity

Author

Christopher B. Murray, Jay A. Schwalbe, Thomas R. Gordon, Sergey Y. Smolin, Jacqueline B. Priebe, Yupeng Lu, Juan José Delgado Jaén, Vicky V. T. Doan-Nguyen, Matteo Cargnello, Tiziano Montini, Paolo Fornasiero, Marga-Martina Pohl, Jason B. Baxter, Angelika Brückner, Ian Salmon McKay, Cargnello, Matteo, Montini, Tiziano, Smolin, Sergey Y., Priebe, Jacqueline B., Jaén, Juan J. Delgado, Doan Nguyen, Vicky V. T., Mckay, Ian S., Schwalbe, Jay A., Pohl, Marga Martina, Gordon, Thomas R., Lu, Yupeng, Baxter, Jason B., Brückner, Angelika, Fornasiero, Paolo, and Murray, Christopher B.

Subjects
Titania, Materials science, Nanostructure, Photoreforming, Quantum yield, Nanotechnology, Brookite, Hydrogen, Photocatalysis, Multidisciplinary, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Reaction rate, Photocatalysi, titania, Hydrogen production, photoreforming, food and beverages, brookite, 021001 nanoscience & nanotechnology, 0104 chemical sciences, hydrogen, Excited state, visual_art, Physical Sciences, visual_art.visual_art_medium, Nanorod, 0210 nano-technology, photocatalysis
Abstract

Photocatalytic pathways could prove crucial to the sustainable production of fuels and chemicals required for a carbon-neutral society. Electron-hole recombination is a critical problem that has, so far, limited the efficiency of the most promising photocatalytic materials. Here, we show the efficacy of anisotropy in improving charge separation and thereby boosting the activity of a titania (TiO2) photocatalytic system. Specifically, we show that H-2 production in uniform, one-dimensional brookite titania nanorods is highly enhanced by engineering their length. By using complimentary characterization techniques to separately probe excited electrons and holes, we link the high observed reaction rates to the anisotropic structure, which favors efficient carrier utilization. Quantum yield values for hydrogen production from ethanol, glycerol, and glucose as high as 65%, 35%, and 6%, respectively, demonstrate the promise and generality of this approach for improving the photoactivity of semiconducting nanostructures for a wide range of reacting systems.

Published
2016

35. Na 2 Ti 3 O 7 Nanoplatelets and Nanosheets Derived from a Modified Exfoliation Process for Use as a High-Capacity Sodium-Ion Negative Electrode.

Author

Ko JS, Doan-Nguyen VV, Kim HS, Muller GA, Serino AC, Weiss PS, and Dunn BS

Abstract

The increasing interest in Na-ion batteries (NIBs) can be traced to sodium abundance, its low cost compared to lithium, and its intercalation chemistry being similar to that of lithium. We report that the electrochemical properties of a promising negative electrode material, Na 2 Ti 3 O 7 , are improved by exfoliating its layered structure and forming 2D nanoscale morphologies, nanoplatelets, and nanosheets. Exfoliation of Na 2 Ti 3 O 7 was carried out by controlling the amount of proton exchange for Na + and then proceeding with the intercalation of larger cations such as methylammonium and propylammonium. An optimized mixture of nanoplatelets and nanosheets exhibited the best electrochemical performance in terms of high capacities in the range of 100-150 mA h g -1 at high rates with stable cycling over several hundred cycles. These properties far exceed those of the corresponding bulk material, which is characterized by slow charge-storage kinetics and poor long-term stability. The results reported in this study demonstrate that charge-storage processes directed at 2D morphologies of surfaces and few layers of sheets are an exciting direction for improving the energy and power density of electrode materials for NIBs.

Published
2017
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36. Infinite Polyiodide Chains in the Pyrroloperylene-Iodine Complex: Insights into the Starch-Iodine and Perylene-Iodine Complexes.

Author

Madhu S, Evans HA, Doan-Nguyen VV, Labram JG, Wu G, Chabinyc ML, Seshadri R, and Wudl F

Abstract

We report the preparation and X-ray crystallographic characterization of the first crystalline homoatomic polymer chain, which is part of a semiconducting pyrroloperylene-iodine complex. The crystal structure contains infinite polyiodide I∞ (δ-) . Interestingly, the structure of iodine within the insoluble, blue starch-iodine complex has long remained elusive, but has been speculated as having infinite chains of iodine. Close similarities in the low-wavenumber Raman spectra of the title compound and starch-iodine point to such infinite polyiodide chains in the latter as well., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Published
2016
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