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Your search keyword '"Stucky, Galen D."' showing total 93 results
Start Over Author "Stucky, Galen D." Journal chemistry of materials
93 results on '"Stucky, Galen D."'

1. Nanostructured Mn-Doped V2O5 Cathode Material Fabricated from Layered Vanadium Jarosite

Author

Zeng, Hongmei, Liu, Deyu, Zhang, Yichi, See, Kimberly A, Jun, Young-Si, Wu, Guang, Gerbec, Jeffrey A, Ji, Xiulei, and Stucky, Galen D

Subjects
Chemical Sciences, Engineering, Materials
Abstract

We propose a nanostructured Mn-doped V2O5 lithium-ion battery cathode material that facilitates cathodic charge transport. The synthesis strategy uses a layered compound, vanadium(III) jarosite, as the precursor, in which the Mn2+ ions are doped uniformly between the vanadium oxide crystal layers. Through a two-step transformation, the vanadium jarosite was converted into Mn2+-doped V2O5. The resulting aliovalent doping of the larger Mn cations in the modified V2O5 structure increases the cell volume, which facilitates diffusion of Li+ ions, and introduces oxygen vacancies that improve the electronic conductivity. Comparison of the electrochemical performance in Li-ion batteries of undoped and the Mn2+-doped V2O5 hierarchical structure made from layered vanadium jarosite confirms that the Mn-doping improves ion transport to give a high cathodic columbic capacity (253 mAhg-1 at 1C, 86% of the theoretical value, 294 mAhg-1) and excellent cycling stability.

Published
2015

2. High Thermoelectric Performance of a Heterogeneous PbTe Nanocomposite

Author

Wang, Hongchao, Hwang, Junphil, Snedaker, Matthew Loren, Kim, Il-ho, Kang, Chanyoung, Kim, Jungwon, Stucky, Galen D, Bowers, John, and Kim, Woochul

Subjects
Chemical Sciences, Engineering, Materials
Abstract

In this paper, we propose a heterogeneous material for bulk thermoelectrics. By varying the quenching time of Na doped PbTe, followed by hot pressing, we synthesized heterogeneous nanocomposites, a mixture of nanodot nanocomposites and nanograined nanocomposites. It is well-known that by putting excess amounts of Na (i.e., exceeding the solubility limit) into PbTe, nanodots with sizes as small as a few nanometers can be formed. Nanograined regions with an average grain size of ca. 10 nm are observed only in materials synthesized with an extremely low quenching rate, which was achieved by using a quenching media of iced salt water and cold water. Dimensionless thermoelectric figures of merit, zT, of those heterogeneous nanocomposites exhibited a zT around 2.0 at 773 K, which is a 25% increase compared to zT of a homogeneous nanodot nanocomposite with the largest quenching time in our experiment, i.e. furnace cooled. The power factor increase is 5%, and the thermal conductivity reduction is 15%; thus, zT increase mainly comes from the thermal conductivity reduction.

Published
2015

3. Heterostructured Approaches to Efficient Thermoelectric Materials

Author

Zhang, Yichi and Stucky, Galen D

Subjects
heterostructures, thermoelectric materials, nanoinclusions, metal-semiconductor, interfacial barrier, hot carrier filtering, Chemical Sciences, Engineering, Materials
Abstract

A key challenge for the materials chemist is the development of controllable and straightforward synthetic methodologies that will integrate multiple phases/compositions with scalar designed physical properties. The intent of this Perspective is to give a brief summary of some of the current bulk-scaled approaches that might help guide researchers in the design of optimal heterostructures in large quantity for the further improvement of thermoelectric conversion efficiency. Examples of two-phase combinations on different length scales will be discussed with a focus on the hot carrier filtering effect that results from the selective scattering of carriers with different energies. On the basis of this strategy, heterostructures fabricated by both the bottom-up solution approaches at low temperature and top-down solid-state deposition routes that show promise in improving the thermoelectric figure of merit are highlighted. © 2013 American Chemical Society.

Published
2014

4. Silicon-Based Thermoelectrics Made from a Boron-Doped Silicon Dioxide Nanocomposite

Author

Snedaker, Matthew L, Zhang, Yichi, Birkel, Christina S, Wang, Heng, Day, Tristan, Shi, Yifeng, Ji, Xiulei, Kraemer, Stephan, Mills, Carolyn E, Moosazadeh, Armin, Moskovits, Martin, Snyder, G Jeffrey, and Stucky, Galen D

Subjects
thermoelectrics, silicon germanium, magnesiothermic reduction, silica, germania, Chemical Sciences, Engineering, Materials
Abstract

We report a method for preparing p-type silicon germanium bulk alloys directly from a boron-doped silica germania nanocomposite. This is the first successful attempt to produce and characterize the thermoelectric properties of SiGe-based thermoelectric materials prepared at temperatures below the alloy's melting point through a magnesiothermic reduction of the silica-germania nanocomposite. We observe a thermoelectric power factor that is competitive with the literature record obtained for high energy ball milled nanocomposites. The large grain size in our hot pressed samples limits the thermoelectric figure of merit to 0.5 at 800 C for an optimally doped Si80Ge20 alloy. © 2013 American Chemical Society.

Published
2013

5. Bimodal Mesoporous Titanium Nitride/Carbon Microfibers as Efficient and Stable Electrocatalysts for Li–O2 Batteries

Author

Park, Jihee, Jun, Young-Si, Lee, Woo-ram, Gerbec, Jeffrey A, See, Kimberly A, and Stucky, Galen D

Subjects
lithium-air battery, metal nitrides, mesoporous materials, molecular cooperative assembly, Chemical Sciences, Engineering, Materials
Abstract

Nonprecious transition metal nitrides have attracted considerable attention as an alternative catalyst to noble metals for electrochemical reactions. Titanium nitride (TiN), in particular, is an interesting material that exhibits excellent thermal, chemical, and mechanical stability, electrical conductivity, and in particular electrocatalytic activity. TiN is often prepared by the nitridation of titanium oxide using gaseous ammonia or hydrazine as a nitrogen source. This high temperature synthesis, however, gives a material with low surface area, which is unfavorable for its application in heterogeneous electrocatalysis. The shape and size of the assembly, and thus the resulting g-CN materials, can be tailored simply by using different precipitation temperatures, solvents, and comonomers. Furthermore, the assembly develops unique nanostructures during the polycondensation without losing the pristine macrostructures.

Published
2013

9. Rapid Microwave Preparation of Thermoelectric TiNiSn and TiCoSb Half-Heusler Compounds

Author

Birkel, Christina S., primary, Zeier, Wolfgang G., additional, Douglas, Jason E., additional, Lettiere, Bethany R., additional, Mills, Carolyn E., additional, Seward, Gareth, additional, Birkel, Alexander, additional, Snedaker, Matthew L., additional, Zhang, Yichi, additional, Snyder, G. Jeffrey, additional, Pollock, Tresa M., additional, Seshadri, Ram, additional, and Stucky, Galen D., additional

Published
2012
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50. HeterostructuredApproaches to Efficient ThermoelectricMaterials.

Author

Zhang, Yichi and Stucky, Galen D.

Subjects
*HETEROSTRUCTURES, *THERMOELECTRIC materials, *CHEMICAL synthesis, *LOW temperatures, *MICROFABRICATION, *SCATTERING (Physics), *ELECTRIC power conversion
Abstract

A key challenge for the materialschemist is the development ofcontrollable and straightforward synthetic methodologies that willintegrate multiple phases/compositions with scalar designed physicalproperties. The intent of this Perspective is to give a brief summaryof some of the current bulk-scaled approaches that might help guideresearchers in the design of optimal heterostructures in large quantityfor the further improvement of thermoelectric conversion efficiency.Examples of two-phase combinations on different length scales willbe discussed with a focus on the hot carrier filtering effect thatresults from the selective scattering of carriers with different energies.On the basis of this strategy, heterostructures fabricated by boththe bottom-up solution approaches at low temperature and top-downsolid-state deposition routes that show promise in improving the thermoelectricfigure of merit are highlighted. [ABSTRACT FROM AUTHOR]

Published
2014
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