Details of a Researcher - Thomas, Morgan

Papers - Thomas, Morgan

Division display 21 - 37 of about 37 ／ All the affair displays >>

Effect of Anion in Glyme-based Electrolyte for Li-O₂ Batteries: Stability/Solubility of Discharge Intermediate

Hoi-Min Kwon, Morgan L. Thomas, Ryoichi Tatara, Azusa Nakanishi, Kaoru Dokko, Masayoshi Watanabe

CHEMISTRY LETTERS (CHEMICAL SOC JAPAN) 46 ( 4 ) 573 - 576 2017.04

Accepted, ISSN 0366-7022

Access to Document (DOI)

Suppression of Water Absorption by Molecular Design of Ionic Liquid Electrolyte for Li-Air Battery

Morgan L. Thomas, Yoshiki Oda, Ryoichi Tatara, Hoi-Min Kwon, Kazuhide Ueno, Kaoru Dokko, Masayoshi Watanabe

ADVANCED ENERGY MATERIALS (WILEY-V C H VERLAG GMBH) 7 ( 3 ) art - 1601753 2017.02

Accepted, ISSN 1614-6832

In this study, the effect of water on the oxygen reduction reaction is initially investigated in aprotic ionic liquids by cyclic voltammetry, revealing that the presence of water significantly deteriorates the reversibility of the oxygen reduction reaction and oxygen evolution reaction, which will be detrimental to performance of a practical lithium-air battery. In order to prevent moisture intrusion from ambient air, a hydrophobic electrolyte is then designed and the moisture content in the electrolyte exposed to ambient air is greatly suppressed, to less than 1 wt% at 30 degrees C and 90% RH (relative humidity). Charge and discharge tests using the hydrophobic electrolyte are reversible for several cycles even in O-2 with a RH of 28%. This approach for enhancing the hydrophobicity of the electrolyte, and thus the inherent equilibrium moisture content, for the Li-air battery demonstrates the possibility for improved stability to ambient moisture.

Access to Document (DOI)

Stability of Glyme Solvate Ionic Liquid as an Electrolyte for Rechargeable Li-O₂ Batteries

Hoi-Min Kwon, Morgan L. Thomas, Ryoichi Tatara, Yoshiki Oda, Yuki Kobayashi, Azusa Nakanishi, Kazuhide Ueno, Kaoru Dokko, Masayoshi Watanabee

ACS APPLIED MATERIALS & INTERFACES (AMER CHEMICAL SOC) 9 ( 7 ) 6014 - 6021 2017.02

Accepted, ISSN 1944-8244

A solvate ionic liquid (SIL) was compared with a conventional organic solvent for the electrolyte of the Li-O-2 battery. An equimolar mixture of triglyme (G3) and lithium bis(trifluoromethanesulfonyl)amide (Li[TFSA]), and a G3/Li[TFSA] mixture containing excess glyme were chosen as the SIL and the conventional electrolyte, respectively. Charge behavior and accompanying gas evolution of the two electrolytes was investigated by electrochemical mass spectrometry (ECMS). From the linear sweep voltammetry performed on an as-prepared cell, we demonstrate that the SIL has a higher oxidative stability than the conventional electrolyte and, furthermore, offers the advantage of lower volatility, which would benefit an open-type lithium-O-2 cell design. Moreover, CO2 evolution during galvanostatic charge was less in the SIL, which implies less side reaction. However, O-2 evolution during charge did not reach the theoretical value in either of the two electrolytes. Several mass spectral fragments were generated during the charge process, which provided evidence for side reactions of glyme-based electrolytes. We further relate the difference in observed discharge product morphology for these electrolytes to the solubility of the superoxide intermediate, determined by rotating ring disk electrode (RRDE) measurements.

Access to Document (DOI)

Sulfur-Based Catholyte Solution with a Glass-Ceramic Membrane for Li-S Batteries

Lina Wang, Yu Zhao, Morgan L. Thomas, Arghya Dutta, Hye Ryung Byon

CHEMELECTROCHEM (WILEY-V C H VERLAG GMBH) 3 ( 1 ) 152 - 157 2016.01

Accepted, ISSN 2196-0216

Shuttling of soluble polysulfide species within electrodes is one of the most challenging issues in lithium-sulfur (Li-S) batteries. The resulting deposition of polysulfide species reduces the conductivity of the metallic Li electrode and the quantity of active material. Here, we demonstrate pronounced suppression of polysulfide shuttle using a sulfide-impermeable glass-ceramic membrane, which is employed as separator between the positive and negative electrodes. As a result, highly stable Li-S electrochemistry occurs in the sulfur-dissolving tetrahydrofuran catholyte solution, which provides good capacity retention and Coulombic efficiency for cycling. This demonstration holds promise for practical next-generation batteries with marked reversibility and the possibility to increase the energy density when equipped with a catholyte flow-through mode.

Access to Document (DOI)

Selective aerobic oxidation of para-xylene in sub- and supercritical water. Part 3: effects of geometry and mixing in laboratory scale continuous reactors

Eduardo Perez, Morgan L. Thomas, Duncan Housley, Paul A. Hamley, Joan Fraga-Dubreuil, Jun Li, Edward Lester, Martyn Poliakoff

RSC ADVANCES (ROYAL SOC CHEMISTRY) 6 ( 14 ) 11289 - 11294 2016.01

Accepted, ISSN 2046-2069

In this paper we report a strong dependence of the observed performance of the catalyst on the geometry and the configuration of laboratory scale reactors in the continuous aerobic oxidation of p-xylene in supercritical water. Small differences, such as the length of the feed pipes protruding into the reactor, have a very large effect on the observed yields and selectivities as well as on the reproducibility of the results. Different reactor designs also exert an influence on the perceived catalyst performance. We demonstrate that these effects are consistent with the relative efficiency of mixing of the reactant streams in the different reactors. The overall conclusion is that caution is required when comparing sets of data derived from studying such reactions even in apparently similar experimental arrangements.

Access to Document (DOI)

In situ synchrotron-based X-ray powder diffraction and micro-Raman study of biomass and residue model compounds at hydrothermal conditions

Morgan L. Thomas, Ian S. Butler, Janusz A. Kozinski

ENERGY SCIENCE & ENGINEERING (WILEY) 3 ( 3 ) 189 - 195 2015.05

Accepted, ISSN 2050-0505

The applications of synchrotron X-ray powder diffraction (XRPD) and laser micro-Raman techniques in an examination of the dissolution, transformation, and gasification of pure cellulose and models for biomass residue under hydrothermal conditions in a diamond-anvil cell are reported. The results contribute to the measurement of in situ time-resolved profiles of biomass reactions, catalyst stability, and residue formation that occur in aqueous fluids at near-and supercritical conditions.

Access to Document (DOI)

A perfluorinated moiety-grafted carbon nanotube electrode for the non-aqueous lithium-oxygen battery

Morgan L. Thomas, Keisuke Yamanaka, Toshiaki Ohta, Hye Ryung Byon

CHEMICAL COMMUNICATIONS (ROYAL SOC CHEMISTRY) 51 ( 19 ) 3977 - 3980 2014.12

Accepted, ISSN 1359-7345

Access to Document (DOI)

A structured three-dimensional polymer electrolyte with enlarged active reaction zone for Li-O₂ batteries

Nadege Bonnet-Mercier, Raymond A. Wong, Morgan L. Thomas, Arghya Dutta, Keisuke Yamanaka, Chihiro Yogi, Toshiaki Ohta, Hye Ryung Byon

SCIENTIFIC REPORTS (NATURE PUBLISHING GROUP) 4 ( 1 ) art - 7127 2014.11

Accepted, ISSN 2045-2322

The application of conventional solid polymer electrolyte (SPE) to lithium-oxygen (Li-O-2) batteries has suffered from a limited active reaction zone due to thick SPE and subsequent lack of O-2 gas diffusion route in the positive electrode. Here we present a new design for a three-dimensional (3-D) SPE structure, incorporating a carbon nanotube (CNT) electrode, adapted for a gas-based energy storage system. The void spaces in the porous CNT/SPE film allow an increased depth of diffusion of O-2 gas, providing an enlarged active reaction zone where Li+ ions, O-2 gas, and electrons can interact. Furthermore, the thin SPE layer along the CNT, forming the core/shell nanostructure, aids in the smooth electron transfer when O-2 gas approaches the CNT surface. Therefore, the 3-D CNT/SPE electrode structure enhances the capacity in the SPE-based Li-O-2 cell. However, intrinsic instability of poly(ethylene oxide) (PEO) of the SPE matrix to superoxide (O-2(center dot-)) and high voltage gives rise to severe side reactions, convincing us of the need for development of a more stable electrolyte for use in this CNT/SPE design.

Access to Document (DOI)

In Situ Synthesis of Bipyramidal Sulfur with 3D Carbon Nanotube Framework for Lithium-Sulfur Batteries

Lina Wang, Yu Zhao, Morgan L. Thomas, Hye Ryung Byon

ADVANCED FUNCTIONAL MATERIALS (WILEY-V C H VERLAG GMBH) 24 ( 15 ) 2248 - 2252 2014.04

Accepted, ISSN 1616-301X

A one-pot synthesis of three-dimensional carbon nanotube frameworks with bipyramidal sulfur particles and the application of these materials for a cathode in lithium-sulfur (Li-S) battery are reported. By simple mixing of multi-walled carbon nanotubes (MWCNTs), sulfur powder, and capping agents in water/tetrahydrofuran, micrometer bipyramidal sulfur particles enclosed with MWCNTs are synthesized. The MWCNTs spontaneously form a 3D conducting network inside and outside the sulfur particle. Along the edge of MWCNT framework, a sulfur particle-free region is present, which comprises approximate to 35 vol% based on the total volume. These sulfur-MWCNT bipyramidal particles are mixed with conductive carbon additive to prepare binder-free cathode for Li-S cells. The Li-S cells deliver a specific discharge capacity of approximate to 1600 mAh g(-1) at 0.05 C on the first cycle. In particular, these Li-S cells show high rate stability and Coulombic efficiency with deep discharge and charge (1.0-3.0 V vs Li/Li+). This resultant performance can arise from 1) homogeneous distribution of the conducting MWCNT framework and the carbon additive coating layer on the sulfur particle, which allow rapid Li+ ion/electrolyte diffusion and mitigation of polysulfide shuttle, respectively, and 2) the sulfur-free buffer space accommodating volume expansion. It is expected that this new cathode design with the simple synthetic process can reduce the number of preparation steps, thus allowing the construction of a low-cost Li-S battery.

Access to Document (DOI)

Utilisation Of Waste Wood For Bioenergy Using Supercritical Water Technology

M.L. Thomas, P. Aggarwal, M.P. Hude, J.B. Sontakke, A.K. Dalai, I.S. Butler, J.A. Kozinski

Proceedings of the World Engineers’ Convention paper - 339 2011.09

Accepted

Hydrothermal Raman microscopy studies of manganese carbonyls

Courtney Calahoo, Mirela M. Barsan, Morgan L. Thomas, Janusz A. Kozinski, Ian S. Butler

VIBRATIONAL SPECTROSCOPY (ELSEVIER SCIENCE BV) 57 ( 1 ) 2 - 7 2011.09

Accepted, ISSN 0924-2031

We present here the application of Raman microscopy in providing simultaneous visual and spectroscopic characterisation of the physical and chemical changes occurring in organometallic materials while undergoing hydrothermal treatment. The effect of water at elevated pressures and temperatures on three prototype manganese carbonyls, Mn-2(CO)(10), (eta(5)-C5H5)Mn(CO)(3) and Mn(CO)(5)Br, was investigated. A Bassett-type hydrothermal diamond-anvil cell (HDAC) was used to subject each compound to conditions of at least 22.1 MPa and 374 degrees C (i.e., beyond the critical point of water), while Raman microscopy was used to monitor the structural changes occurring during the heating and cooling cycles of the cell. The hydrothermal studies showed that Mn-2(CO)(10), (eta(5)-C5H5)Mn(CO)(3) and Mn(CO)(5)Br dissolved in subcritical water at 150, 125 and 225 degrees C. respectively. Moreover, Mn(CO)(5)Br is also believed to have dimerized to Mn-2(CO)(8)Br-2 when the cell temperature was increased to 425 degrees C. (C) 2011 Elsevier B.V. All rights reserved.

Access to Document (DOI)

Frontiers In Energy Science And Engineering: A Canadian Perspective

M.L. Thomas, J.A. Kozinski

Proceedings of the World Engineers’ Convention paper - 447 2011.09

Accepted

Selective aerobic oxidation of para-xylene in sub- and supercritical water. Part 2. The discovery of better catalysts

Eduardo Perez, Joan Fraga-Dubreuil, Eduardo Garcia-Verdugo, Paul A. Hamley, Morgan L. Thomas, Chong Yan, W. Barry Thomas, Duncan Housley, Walt Partenheimer, Martyn Poliakoff

GREEN CHEMISTRY (ROYAL SOC CHEMISTRY) 13 ( 9 ) 2397 - 2407 2011.07

Accepted, ISSN 1463-9262

An extensive and systematic study has been carried out on the catalytic effect of more than 20 elements on the aerobic oxidation of p-xylene to terephthalic acid in super-and subcritical water. Reactions have been performed in a continuous reactor under catalyst unsaturated conditions. Reaction product, by-products and intermediates have been quantified as well as the burn (the amount of CO2 originating from total oxidation of p-xylene). CuBr2 has been found to be a superior catalyst to MnBr2, which has been widely used in the literature for this reaction in water at high temperatures. At catalyst unsaturated conditions (i.e. with low concentrations of catalyst), MnBr2 gives a terephthalic acid yield of 36.1% whereas CuBr2 enhances this value to 55.6%. A strong synergistic effect has been found between CuBr2 and other metals and sources of bromide. Indeed, we show that Cu/Co/Br, Cu/Co/NH4/Br and other mixtures give better results than CuBr2 reaching a terephthalic acid yield of 70.5% for the four component catalyst. The compositions of the catalyst as well as the reactor temperature have been optimized and their effects on the analyzed compounds are discussed. A substantial amount of additional data is included in the electronic supplementary information.

Access to Document (DOI)

Advanced Analytical Methods in the Study of Waste Combustion: Recent Advances with in situ Synchrotron-based Measurements

M.L. Thomas, A.K. Dalai, I.S. Butler, J.A. Kozinski

Proceedings of the Combustion Institute / Canadian Section Spring Technical Meeting 329 - 332 2011.05

Accepted

Entwicklung eines Prozesses zur Herstellung von 2-Methyltetrahydrofuran als Kraftstoffkomponente

A. Harwardt, M. Thomas, F. Geilen, W. Leitner, W. Marquardt

Chemie Ingenieur Technik (Wiley-Blackwell) 81 ( 8 ) 1202 - 1203 2009.08

Access to Document (DOI)

Catalysis in High Temperature Water

Morgan L. Thomas

2008.07

A dramatic switch in selectivity in the catalytic dehydrogenation of 4-vinylcyclohexene in high pressure steam; a cautionary lesson for continuous flow reactions

Morgan L. Thomas, Joan Fraga-Dubreuil, A. Stuart Coote, Martyn Poliakoff

GREEN CHEMISTRY (ROYAL SOC CHEMISTRY) 10 ( 2 ) 197 - 201 2007.11

Accepted, ISSN 1463-9262

We report an investigation of the continuous oxidative dehydrogenation of 4-vinylcyclohexene (VCH) in high pressure steam. Oxidative dehydrogenation reactions such as this are often limited by unselective or total oxidation. We find that these side-reactions not only occur in this case, but can also have a major influence on the selectivity; a small increase in flow rate results in a complete switch in selectivity of the reaction. Our results suggest that styrene (ST) is formed as the initial product but that unless the H-2 is sequestered, ST may then be hydrogenated to yield ethylbenzene (EB).
The observation of periodic temperature spikes near the surface of the catalyst bed indicate cycles of propagating flames occur in a relatively small volume of the reactor, leading to total oxidation of some VCH and removal of O-2, which would otherwise sequester the H-2. These flames give rise to the large variations in the observed product selectivity. We suggest that these observations may not be restricted to this reaction system and reactor configuration, and may occur in other situations where small-scale continuous flow oxidation reactors are used.

Access to Document (DOI)

　 Previous page - Next page 　