九州大学 研究者情報
LYTH STEPHEN(ライス スティーブン) データ更新日:2021.06.21

准教授 /  エネルギー研究教育機構

1. Bayer, Thomas; Cunning, Benjamin Vaughan; Smid, Bretislav; Selyanchyn, Roman; Fujikawa, Shigenori; Sasaki, Kazunari; Lyth, Stephen Matthew, Spray deposition of sulfonated cellulose nanofibers as electrolyte membranes in fuel cells, CELLULOSE, 10.1007/s10570-020-03593-w, 28, 3, 1355-1367, 2021.02.
2. Selyanchyn, Olena; Selyanchyn, Roman; Lyth, Stephen M., A Review of Proton Conductivity in Cellulosic Materials, FRONTIERS IN ENERGY RESEARCH, 10.3389/fenrg.2020.596164, 8, 2020.11.
3. Masahiro Yasutake, Daiki Kawachino, Zhiyun Noda, Junko Matsuda, Stephen M. Lyth,Kohei Ito,Akari Hayashi, and Kazunari Sasaki, Catalyst-Integrated Gas Diffusion Electrodes for Polymer Electrolyte Membrane Water Electrolysis: Porous Titanium Sheets with Nanostructured TiO2 Surfaces Decorated with Ir Electrocatalysts, Journal of The Electrochemical Society, DOI: 10.1149/1945-7111/abb37d, 167, 124523, 2020.10.
4. Ishibashi, Yusuke; Matsumoto, Kohei; Futamura, Shotaro; Tachikawa, Yuya; Matsuda, Junko; Lyth, Stephen M.; Shiratori, Yusuke; Taniguchi, Shunsuke; Sasaki, Kazunari, Improved Redox Cycling Durability in Alternative Ni Alloy-Based SOFC Anodes, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 10.1149/1945-7111/abac87, 167, 12, 2020.01.
5. Kawachino, D.; Yasutake, M.; Noda, Z.; Matsuda, J.; Lyth, S. M.; Hayashi, A.; Sasaki, K., Surface-Modified Titanium Fibers as Durable Carbon-Free Platinum Catalyst Supports for Polymer Electrolyte Fuel Cells, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 10.1149/1945-7111/ab9cd4, 167, 10, 2020.06.
6. Albert Mufundirwa, George F. Harrington, Mohammed S. Ismail, Šmid Břetislav, Benjamin V. Cunning, Yu Shundo, Mohamed Pourkashanian, Kazunari Sasaki, Akari Hayashi, Stephen M. Lyth, Gram-scale synthesis of alkoxide-derived nitrogen-doped carbon foam as a support for Fe-N-C electrocatalysts, Nanotechnology, 10.1088/1361-6528/ab76ed, 31, 22, 2020.05, [URL], Non-platinum group metal (non-PGM) catalysts for the oxygen reduction reaction (ORR) are set to reduce the cost of polymer electrolyte membrane fuel cells (PEFCs) by replacing platinum at the cathode. We previously developed unique nitrogen-doped carbon foams by template-free pyrolysis of alkoxide powders synthesized using a high temperature and high pressure solvothermal reaction. These were shown to be effective ORR electrocatalysts in alkaline media. Here, we present a new optimised synthesis protocol which is carried out at ambient temperature and pressure, enabling us to safely increase the batch size to 2 g, increase the yield by 60%, increase the specific surface area to 1866 m2 g-1, and control the nitrogen content (between 1.0 and 5.2 at%). These optimized nitrogen-doped carbon foams are then utilized as effective supports for Fe-N-C catalysts for the ORR in acid media, whilst multiphysics modelling is used to gain insight into the electrochemical performance. This work highlights the importance of the properties of the carbon support in the design of Pt-free electrocatalysts..
7. K. Takino, Y. Tachikawa, K. Mori, S. M. Lyth, Y. Shiratori, S. Taniguchi, K. Sasaki, Simulation of SOFC performance using a modified exchange current density for pre-reformed methane-based fuels, International Journal of Hydrogen Energy, 10.1016/j.ijhydene.2019.12.089, 45, 11, 6912-6925, 2020.02, [URL], Numerical simulations can be used to visualize and better understand various distributions such as gas concentration and temperature in solid oxide fuel cells (SOFCs) under realistic operating conditions. However, pre-existing models generally utilize an anode exchange current density equation which is valid for humidified hydrogen fuels – an unrealistic case for SOFCs, which are generally fueled by hydrocarbons. Here, we focus on developing a new, modified exchange current density equation, leading to an improved numerical analysis model for SOFC anode kinetics. As such, we experimentally determine the exchange current density of SOFC anodes fueled by fully pre-reformed methane. The results are used to derive a new phenomenological anode exchange current density equation. This modified equation is then combined with computational fluid dynamics (CFD) to simulate the performance parameters of a three-dimensional electrolyte-supported SOFC. The new modified exchange current density equation for methane-based fuels reproduces the I–V characteristics and temperature distribution significantly better than the previous models using humidified hydrogen fuel. Better simulations of SOFC performance under realistic operating conditions are crucial for the prediction and prevention of e.g. fuel starvation and thermal stresses..
8. Prabakaran Saravanan, Roman Selyanchyn, Hiroyoshi Tanaka, Shigenori Fujikawa, Stephen Matthew Lyth, Joichi Sugimura, The effect of oxygen on the tribology of (PEI/GO)15 multilayer solid lubricant coatings on steel substrates, Wear, 10.1016/j.wear.2019.05.035, 432-433, 2019.08, [URL], Multilayers of polyethyleneimine and graphene oxide, (PEI/GO)15, were coated onto steel substrates via electrostatic layer-by-layer (LbL) deposition, and their tribological properties were investigated as solid lubricants. The coefficient of friction (COF) and specific wear rate (SWR) were measured against a poly(methyl methacrylate) (PMMA) counterface ball, in various gas environments with different oxygen concentrations. The COF and SWR both significantly decreased with decreasing oxygen content. Detailed surface characterization of the contact area of the counterface ball revealed that continuous transfer films were formed in oxygen-free environments, but not in oxygen-rich environments. This is attributed to an increased proportion of sp3 bonding in the wear debris in the presence of oxygen (as confirmed by Raman spectroscopy), as well as possible suppression of wear debris adhesion on the counterface ball due to oxygen adsorption on the surface..
9. S. Futamura, A. Muramoto, Y. Tachikawa, J. Matsuda, S. M. Lyth, Y. Shiratori, S. Taniguchi, K. Sasaki, SOFC anodes impregnated with noble metal catalyst nanoparticles for high fuel utilization, 16th International Symposium on Solid Oxide Fuel Cells, SOFC 2019
Solid Oxide Fuel Cells 16, SOFC 2019
, 10.1149/09101.1905ecst, 1905-1913, 2019.01, [URL], In order to improve the stability under high fuel utilization, alternative anodes are fabricated with ionic (mixed) conducting GDC (Ce0.9Gd0.1O2) and electronic conducting LST (Sr0.9La0.1TiO3), both of which act as stable ion- and electron-conducting frameworks against reduction-oxidation (redox) cycles, respectively. Noble metal catalyst nanoparticles (Rh, Pt, or Pd) are incorporated via impregnation with GDC on the LST-GDC backbones. The electrochemical characteristics, such as the stability against redox cycling and under high fuel utilization, of SOFC single cells using these anodes are characterized in humidified H2 at 800°C. Moreover, the changes of the noble metal catalyst nanoparticles before/after the high fuel utilization durability tests are analyzed and discussed..
10. Berend Smit, Richard Graham, Peter Styring, Joseph Yao, Peter Clough, Jet Sing M. Lee, Niall Macdowell, Stephen Matthew Lyth, Gary Rochelle, Thomas Hills, Grant Wilson, Camille Petit, Jasmin Kemper, Rosa Cuellar-Franca, George Dowson, Matteo Gazzani, Paul Fennell, Daniel Sutter, Colin Scholes, Adisa Azapagic, Robert Bell, Jon Gibbins, Marco Mazzotti, Geoffrey Maitland, Stefano Brandani, Raffaella Ocone, Mayte Teresa Mota-Martinez, Matthew Dunstan, Peiting Liang, Rahul Anantharaman, Lisa Joss, Joshuah Stolaroff, CCS-A technology for the future
General discussion, Faraday Discussions, 10.1039/c6fd90053d, 192, 303-335, 2016.01, [URL].
11. Tatsuya Kawasaki, Junko Matsuda, Yuya Tachikawa, Stephen Matthew Lyth, Yusuke Shiratori, Shunsuke Taniguchi, Kazunari Sasaki, Oxidation-induced degradation and performance fluctuation of solid oxide fuel cell Ni anodes under simulated high fuel utilization conditions, International Journal of Hydrogen Energy, 10.1016/j.ijhydene.2019.02.136, 44, 18, 9386-9399, 2019.04, [URL], High fuel utilization (Uf) conditions in a small-scale electrolyte-supported solid oxide fuel cell (SOFC) with an Ni-ScSZ anode were approximated by adjusting the gas composition to correspond to that in the downstream region of an SOFC stack. At Uf = 80%, and with a cell voltage of 0.5 V, the ohmic resistance fluctuated slightly from the early stages of operation, and became much more significant after 80 h. High current density and large polarization were found to promote Ni agglomeration, leading to insufficient connectivity of the Ni nanoparticles. At Uf = 95%, and with a cell voltage of 0.6 V, fluctuations in the polarization were observed at a much earlier stage, which are attributed to the highly humidified fuel. In particular, significant degradation was observed when the compensated anode potential (which incorporates the anode ohmic losses) approached the Ni oxidation potential. Ohmic losses in the anode are considered to influence Ni oxidation by exposing Ni near the electrolyte to a more oxidizing atmosphere with the increase in oxygen ion transport. Stable operation is therefore possible under conditions in which the compensated anode potential does not approach the Ni oxidation potential, assuming a stable interconnected Ni network..
12. Shotaro Futamura, Aki Muramoto, Yuya Tachikawa, Junko Matsuda, Stephen Matthew Lyth, Yusuke Shiratori, Shunsuke Taniguchi, Kazunari Sasaki, SOFC anodes impregnated with noble metal catalyst nanoparticles for high fuel utilization, International Journal of Hydrogen Energy, 10.1016/j.ijhydene.2019.01.223, 44, 16, 8502-8518, 2019.03, [URL], Redox-stable solid oxide fuel cell (SOFC) anodes are developed in order to improve durability at higher fuel utilization, as a possible alternative to conventional Ni-zirconia cermet anodes. Ce 0.9 Gd 0.1 O 2 (GDC) is utilized as a mixed ionic and electronic conductor (MIEC), in combination with Sr 0.9 La 0.1 TiO 3 (LST) as an electronic conductor. The stability of noble metals (Rh, Pt, and Pd) is analyzed via thermochemical calculation of stable phases. Noble metal catalyst nanoparticles are incorporated via co-impregnation with GDC. The electrochemical characteristics of SOFC single cells using these anode materials are investigated in highly-humidified H 2 at 800 °C. Their stability at high fuel utilization is analyzed. These co-impregnated anodes with highly dispersed noble metal catalysts on the LST-GDC conducting backbones, achieve high I[sbnd]V performance comparable to conventional Ni-cermet anodes. The co-impregnated anodes also achieve considerably high catalytic mass activity. At higher oxygen partial pressure, where the Ni catalyst can be deactivated by oxidation, these noble catalysts are thermochemically stable in the metallic state, and tolerant against oxidation. This class of alternative catalyst, impregnated with low-loading of noble metals could contribute to stable operation in the downstream region of SOFC systems. A simple cost analysis indicates a tolerance of using noble metals, provided their loading is sufficiently low..
13. Prabakaran Saravanan, Roman Selyanchyn, Motonori Watanabe, Shigenori Fujikawa, Hiroyoshi Tanaka, Stephen Matthew Lyth, Joichi Sugimura, Ultra-low friction of polyethylenimine / molybdenum disulfide (PEI/MoS2)15 thin films in dry nitrogen atmosphere and the effect of heat treatment, Tribology International, 10.1016/j.triboint.2018.06.003, 127, 255-263, 2018.11, [URL], The unique frictional behavior of polyethylenimine/molybdenum disulphide (PEI/MoS2)n thin films on steel substrates, deposited via the layer-by-layer (LbL) technique, is explored. The effects of gaseous atmosphere (i.e. air vs. dry nitrogen), and heat treatment of the coatings are investigated. The coefficients of friction (COFs) are reduced by factors of ca. 2 and 11 in air and N2 respectively, compared to an uncoated steel substrate. Ultra-low friction (COF < 0.02) is achieved in dry N2. After heat treatment of the coating at 500 °C, the COF in air and nitrogen does not change significantly, but the coating demonstrates much higher durability. Detailed characterization of the coating and wear debris are performed to understand the origin of these tribological properties..
14. Y. Nakazato, D. Kawachino, Z. Noda, Junko Matsuda, Stephen Matthew Lyth, Akari Hayashi, Kazunari Sasaki, PEFC electrocatalysts supported on Nb-SnO
for MEAs with high activity and durability
Part I. Application of different carbon fillers, Journal of the Electrochemical Society, 10.1149/2.0311814jes, 165, 14, F1154-F1163, 2018.01, [URL], Currently, carbon black is widely used as an electrocatalyst support for polymer electrolyte fuel cells (PEFCs). However, electrochemical oxidation leads to degradation of this material. In contrast, tin oxide (SnO2) is electrochemically stable even under strongly acidic conditions, and relatively high electronic conductivity can be achieved by doping with niobium (Nb-SnO2), compared with other metal oxides. In this study, Nb-SnO
is composited with various conductive carbon fillers, including vapor-grown carbon fibers (VGCF), carbon nanotubes (CNT), and graphitized carbon black (GCB), followed by platinum nanoparticle decoration. These nanocomposite electrocatalysts are incorporated into membrane electrode assemblies (MEAs) and tested under PEFC operational conditions. The resulting fuel cells achieve high initial I-V performance up to 0.742 V at 0.2 A cm

C), as well as excellent cycling durability. In particular, MEAs fabricated with Pt/Nb-SnO
/VGCF cathode electrocatalysts exhibit remarkable durability, with only a 12.1% drop in cell voltage at 0.2 A cm
over 60,000 start-stop cycles, and a 42.9% drop over 400,000 load potential cycles, corresponding to the lifetime of a fuel cell vehicle (FCV). Platinum-decorated metal oxide electrocatalysts can simultaneously realize high catalytic activity and extended durability, not only in ex-situ half-cell measurements, but also in full cell conditions..
15. S. Matsumoto, M. Nagamine, Z. Noda, Junko Matsuda, Stephen Matthew Lyth, A. Hayashi, Kazunari Sasaki, PEFC electrocatalysts supported on Nb-SnO
for MEAs with high activity and durability
Part II. Application of bimetallic Pt-alloy catalysts, Journal of the Electrochemical Society, 10.1149/2.0321814jes, 165, 14, F1164-F1175, 2018.01, [URL], Bimetallic Pt-alloys supported on niobium-doped tin oxide (Nb-SnO2) with a vapor-grown carbon fiber (VGCF) backbone are presented as electrocatalysts for polymer electrolyte membrane fuel cells (PEFCs). These can simultaneously achieve both high catalytic activity and high cycling durability for the oxygen reduction reaction (ORR). This was confirmed both in half-cell and full-cell membrane electrode assembly (MEA) configuration, using 60,000 start-stop potential cycles and 400,000 load potential cycles. In this study, we focus on alloying Pt with Co or Ni, and the best performance is achieved for Pt
/VGCF electrocatalysts. The catalyst particles are selectively decorated on the Nb-SnO
, resulting in improved resistance to carbon corrosion. Pt
Co alloying was verified by FE-SEM and high-resolution STEM-EDS. High initial mass activity of 274 A g
at 0.9 V
and 1840 A g
at 0.85 V
was achieved, with enhanced durability compared to conventional Pt/C electrocatalysts..
16. Andrea Zitolo, Nastaran Ranjbar-Sahraie, Tzonka Mineva, Jingkun Li, Qingying Jia, Serban Stamatin, George F. Harrington, Stephen Matthew Lyth, Petr Krtil, Sanjeev Mukerjee, Emiliano Fonda, Frédéric Jaouen, Identification of catalytic sites in cobalt-nitrogen-carbon materials for the oxygen reduction reaction, Nature Communications, 10.1038/s41467-017-01100-7, 8, 1, 2017.12, [URL], Single-atom catalysts with full utilization of metal centers can bridge the gap between molecular and solid-state catalysis. Metal-nitrogen-carbon materials prepared via pyrolysis are promising single-atom catalysts but often also comprise metallic particles. Here, we pyrolytically synthesize a Co-N-C material only comprising atomically dispersed cobalt ions and identify with X-ray absorption spectroscopy, magnetic susceptibility measurements and density functional theory the structure and electronic state of three porphyrinic moieties, CoN4C12, CoN3C10, and CoN2C5. The O2 electro-reduction and operando X-ray absorption response are measured in acidic medium on Co-N-C and compared to those of a Fe-N-C catalyst prepared similarly. We show that cobalt moieties are unmodified from 0.0 to 1.0 V versus a reversible hydrogen electrode, while Fe-based moieties experience structural and electronic-state changes. On the basis of density functional theory analysis and established relationships between redox potential and O2-adsorption strength, we conclude that cobalt-based moieties bind O2 too weakly for efficient O2 reduction..
17. Masamichi Nishihara, Y. Terayama, T. Haji, Stephen Matthew Lyth, S. Satokawa, Hiroshige Matsumoto, Proton-conductive nano zeolite-PVA composite film as a new water-absorbing electrolyte for water electrolysis, Express Polymer Letters, 10.3144/expresspolymlett.2018.23, 12, 3, 256-264, 2018.03, [URL], In this study, organic-inorganic composite electrolyte membranes are developed for a novel water-absorbing porous electrolyte water electrolysis cell. As the materials of the composite electrolyte membrane, 80 wt% of a proton-con-ducting nano zeolite (H-MFI) as an electrolyte and 20 wt% of poly(vinyl alcohol) (PVA) as a cross-linkable matrix are used. The nano zeolite is prepared by a milling process. The nano zeolite-PVA composite membrane precursors are prepared by spraying onto a substrate, followed by cross-linking. The resulting nano zeolite-cross-linked PVA composite films are then evaluated for their properties such as proton conductivity as electrolyte membranes for the water-absorbing porous electrolyte water electrolysis cell. It is confirmed that conventional materials such as zeolites and PVA can be used for the water electrolysis as an electrolyte..
18. Albert Mufundirwa, George F. Harrington, Břetislav Smid, Benjamin V. Cunning, Kazunari Sasaki, Stephen Matthew Lyth, Durability of template-free Fe-N-C foams for electrochemical oxygen reduction in alkaline solution, Journal of Power Sources, 10.1016/j.jpowsour.2017.07.025, 375, 244-254, 2018.01, [URL], Due to the high cost and limited availability of platinum, the development of non-platinum-group metals (non-PGM) catalysts is of paramount importance. A promising alternative to Pt are Fe-N-C-based materials. Here we present the synthesis, characterization and electrochemistry of a template-free nitrogen-doped carbon foam, impregnated with iron. This low-cost and gram-scale method results in materials with micron-scale pore size and large surface area (1600 m2g-1). When applied as an oxygen reduction reaction (ORR) electrocatalyst in alkaline solution, the Fe-N-C foams display extremely high initial activity, slightly out-performing commercially available non-PGM catalysts (NCP-2000, Pajarito Powder). The load-cycle durability in alkaline solution is investigated, and the performance steadily degrades over 60,000 potential cycles, whilst the commercial catalyst is remarkably stable. The post-operation catalyst microstructure is elucidated by transmission electron microscopy (TEM), to provide insight into the degradation processes. The resulting images suggest that potential cycling leads to leaching of atomically dispersed Fe-N2/4 sites in all the catalysts, whereas encapsulated iron nanoparticles are protected..
19. Aki Muramoto, Yudai Kikuchi, Yuya Tachikawa, Stephen Matthew Lyth, Yusuke Shiratori, Shunsuke Taniguchi, Kazunari Sasaki, High-pressure C-H-O diagrams
Fuel composition, carbon deposition, and open circuit voltage of pressurized SOFCs, International Journal of Hydrogen Energy, 10.1016/j.ijhydene.2017.10.122, 42, 52, 30769-30786, 2017.12, [URL], Solid oxide fuel cells (SOFCs) can operate by using various fuel species. Pressurized SOFCs with gas/steam turbine(s) may achieve higher power generation efficiency as hybrid or triple-combined power generation systems. In this study, fuel gas composition is systematically investigated by thermochemical equilibrium calculations on the anode side of SOFCs, pressurized up to 30 bar over a wide temperature range, up to 1000 °C. Since conventional hydrogen-containing fuel gas consists mainly of carbon, hydrogen, and oxygen, high-pressure C-H-O equilibrium diagrams are numerically obtained. It is revealed that the carbon deposition region contracts in the hydrogen-rich area and expands in the oxygen-rich area with increasing total pressure. The molar fraction of each gas component, described in such C-H-O diagrams, also depends on the total pressure. The theoretical open circuit voltage (OCV) increases by pressurization. The effect of nitrogen in high-pressure SOFC fuels is also considered, which is important especially for air-blown coal gas. The minimum amount of H2O, O2, and CO2 required to prevent carbon deposition in steam reforming, partial oxidation, and CO2 (dry) reforming, respectively, is also derived up to 30 bar. The high-pressure C-H-O diagrams are also applicable to various high-temperature/high-pressure energy systems such as solid oxide electrolyzer cells (SOECs) and reversible fuel cells..
20. Prabakaran Saravanan, Roman Selyanchyn, Hiroyoshi Tanaka, Shigenori Fujikawa, Stephen Matthew Lyth, Joichi Sugimura, Ultra-low friction between polymers and graphene oxide multilayers in nitrogen atmosphere, mediated by stable transfer film formation, Carbon, 10.1016/j.carbon.2017.06.090, 122, 395-403, 2017.10, [URL], The efficiency and lifetime of mechanical devices is significantly decreased by friction and wear, significantly contributing to global energy consumption. We previously showed that multilayer polyethyleneimine/graphene oxide thin films, (PEI/GO)15, on steel display superlubricity against a steel counterface ball. Here, the coefficient of friction (COF) and wear of (PEI/GO)15 with six different counterface polymer balls is investigated in air and in nitrogen, with particular focus on the formation of tribological transfer films. The polymers polyoxymethylene (POM), polyetheretherketone (PEEK), polyethylene (PE), poly(methyl methacrylate) (PMMA), polycarbonate (PC), and polytetrafluoroethylene (PTFE) are utilized. The COF of (PEI/GO)15 vs steel is 0.35 in both air and nitrogen. In air, the COF ranges from 0.06 to 0.17 for all polymers. Significantly, in nitrogen, four polymers (POM, PEEK, PMMA and PC) display ultra-low friction (COF ∼0.02) whilst two do not (PTFE and PE). The wear tracks and transfer films are investigated using e.g. optical microscopy, electron microscopy, and Raman mapping, and the tribological behavior is correlated to the hydrophilicity and relative hardness of the polymer balls compared to GO..
21. Sichao Ma, Jianfeng Liu, Kazunari Sasaki, Stephen Matthew Lyth, Paul J.A. Kenis, Carbon Foam Decorated with Silver Nanoparticles for Electrochemical CO2 Conversion, Energy Technology, 10.1002/ente.201600576, 5, 6, 861-863, 2017.06, [URL], Electrochemistry is a promising method to recycle CO2 into useful carbon feedstock and for storing intermittent renewable energy. To date, Au and Ag nanoparticles are the most active catalysts for electrochemical conversion of CO2 to CO. However, agglomeration reduces the activity and the high cost slows widespread commercialization. Suitable support materials are thus needed to improve catalyst utilization. We explore carbon foam (CF) as a catalyst support. Compared with carbon black or graphene nanoplatelets, CF has higher surface area, larger pores, and more defects, resulting in improved uniformity of Ag nanoparticle distribution as well as higher activity and efficiency for CO2 conversion to CO..
22. S. Futamura, Yuya Tachikawa, Junko Matsuda, Stephen Matthew Lyth, Yusuke Shiratori, Shunsuke Taniguchi, Kazunari Sasaki, Alternative SOFC anode materials with ion- and electron-conducting backbones for higher fuel utilization, 15th International Symposium on Solid Oxide Fuel Cells, SOFC 2017
ECS Transactions
, 10.1149/07801.1179ecst, 78, 1179-1187, 2017.05, [URL], Redox-stable anodes are developed for zirconia-based electrolyte-supported solid oxide fuel cells (SOFCs) operating at high fuel utilization, as an alternative to the Ni yttrium-stabilized-zirconia (YSZ) cermet. Gadolinium-doped ceria (GDC, Ce0.9Gd0.1O2) is utilized as a mixed ionic electronic conductor (MIEC), and combined with lanthanum-doped strontium titanate (LST, Sr0.9La0.1TiO3) as an electronic conductor. Catalyst nanoparticles (either Ni or Rh) are incorporated via impregnation. The electrochemical characteristics of SOFC single cells using these anodes are characterized in humidified H2 at 800°C. The stability against redox cycling and under high fuel utilization is analyzed and discussed..
23. J. Sugimoto, S. Futamura, T. Kawabata, Stephen Matthew Lyth, Yusuke Shiratori, Shunsuke Taniguchi, Kazunari Sasaki, Ru-based SOFC anodes
Preparation, performance, and durability, International Journal of Hydrogen Energy, 10.1016/j.ijhydene.2017.01.028, 42, 10, 6950-6964, 2017.03, [URL], Ru-based solid oxide fuel cell (SOFC) cermet anodes are presented. The preparation conditions of the Ru-based anodes are adjusted by preventing the sublimation of Ru-oxides at elevated temperatures by using an oxidizing atmosphere. SOFC single cells with zirconia-electrolyte and cathode are prepared, and the electrochemical performance is examined using realistic fuels containing low concentrations of higher hydrocarbons and trace sulfur impurities. The degradation rate is relatively high under simulated high fuel utilization operating conditions. However, under the operational condition near the fuel inlet of SOFC systems, the Ru-based anode satisfies 5000-h durability by using hydrocarbon-containing fuels. While a much higher durability is needed for stationary applications, the cells with the Ru-based anode may be applicable to e.g. automobile applications with hydrocarbon-containing fuels as high internal reforming activity, carbon deposition tolerance, and sulfur impurity tolerance have been verified..
24. Matthias Breitwieser, Thomas Bayer, Andreas Büchler, Roland Zengerle, Stephen Matthew Lyth, Simon Thiele, A fully spray-coated fuel cell membrane electrode assembly using Aquivion ionomer with a graphene oxide/cerium oxide interlayer, Journal of Power Sources, 10.1016/j.jpowsour.2017.03.085, 351, 145-150, 2017.01, [URL], A novel multilayer membrane electrode assembly (MEA) for polymer electrolyte membrane fuel cells (PEMFCs) is fabricated in this work, within a single spray-coating device. For the first time, direct membrane deposition is used to fabricate a PEMFC by spraying the short-side-chain ionomer Aquivion directly onto the gas diffusion electrodes. The fully sprayed MEA, with an Aquivion membrane 10 μm in thickness, achieved a high power density of 1.6 W/cm2 for H2/air operation at 300 kPaabs. This is one of the highest reported values for thin composite membranes operated in H2/air atmosphere. By the means of confocal laser scanning microscopy, individual carbon fibers from the gas diffusion layer are identified to penetrate through the micro porous layer (MPL), likely causing a low electrical cell resistance in the range of 150 Ω cm2 through the thin sprayed membranes. By spraying a 200 nm graphene oxide/cerium oxide (GO/CeO2) interlayer between two layers of Aquivion ionomer, the impact of the electrical short is eliminated and the hydrogen crossover current density is reduced to about 1 mA/cm2. The peak power density of the interlayer-containing MEA drops only by 10% compared to a pure Aquivion membrane of similar thickness..
25. S. Futamura, Yuya Tachikawa, Junko Matsuda, Stephen Matthew Lyth, Yusuke Shiratori, Shunsuke Taniguchi, Kazunari Sasaki, Alternative Ni-impregnated mixed ionic-electronic conducting anode for SOFC operation at high fuel utilization, Journal of the Electrochemical Society, 10.1149/2.0071710jes, 164, 10, F3055-F3063, 2017.01, [URL], Redox-stable anodes are developed for zirconia-based electrolyte-supported SOFCs in order to improve the durability against fuel supply interruption and for higher fuel utilization, as an alternative to the conventional Ni-YSZ cermet. GDC (Ce0.9Gd0.1O2) is utilized as a mixed ionic-electronic conductor (MIEC), and combined with LST (Sr0.9La0.1TiO3) as an electronic conductor. Ni catalyst nanoparticles are incorporated via impregnation. The electrochemical characteristics of SOFC single cells using these anode materials are investigated in humidified H2 at 800°C. The stability against redox cycling and under high fuel utilization is analyzed and discussed. Ni-impregnated anodes with dispersed Ni catalyst nanoparticles on conducting oxide LST-GDC backbones exhibit lower anode non-ohmic overvoltage, and improve I-V performance. These anodes also show better redox stability compared to conventional anodes because of the isolation of Ni catalysts, preventing their agglomeration. Moreover, the co-impregnation of Ni catalysts and GDC nanoparticles further improves electrochemical characteristics due to a decrease in anode ohmic (IR) loss and non-ohmic overvoltage. This anode shows comparable I-V performance to conventional anodes for typical humidified hydrogen fuels, and is a promising redox-stable alternative for application at high fuel utilization..
26. Yuki Terayama, Takamasa Haji, Shoichi Furukawa, Munemitsu Nomura, Masamichi Nishihara, Stephen Matthew Lyth, Yoshitsugu Sone, Hiroshige Matsumoto, Carbon black / PTFE composite hydrophobic gas diffusion layers for a water-absorbing porous electrolyte electrolysis cell, International Journal of Hydrogen Energy, 10.1016/j.ijhydene.2017.12.045, 2017.01, [URL], The characteristics of a water-absorbing porous electrolyte electrolysis cell, in which pressurized water is injected directly into the electrolyte layer, are investigated. High water support force is required for the gas diffusion layer (GDL) in this novel cell design, and therefore here we report a new type of hydrophobic GDL comprising an acetylene black (AB) and poly(tetrafluoroethylene) (PTFE) composite film. The method of preparation of the AB/PTFE slurry, film formation methods, and the AB/PTFE weight ratio were investigated and optimized. The ball-milling and transfer method were suitable for preparing uniform AB/PTFE slurry and successfully covering AB/PTFE film without any cracks on micro-porous layer coated carbon paper, respectively. An investigation about different PTFE weight ratios against AB from 0.1 to 6 showed a serious trade-off character between electrical resistance R, gas permeability V', and water support force P lim. The 1/2.5 of AB/PTFE weight ratio was most optimal, which showed to have most equivalent R (2.5 Ω cm-2), V'(136 mL atm-1 cm-2 min-1), and P lim (0.25 MPa). We also confirmed that fabricated GDL with optimal condition was worked as the blocking layer against water injected through electrolyte layer and pressurized by nitrogen gas, and as gas-permeation layer for generated hydrogen gas in water electrolysis test..
27. M. Okumura, Z. Noda, Junko Matsuda, Yuya Tachikawa, Masamichi Nishihara, Stephen Matthew Lyth, Akari Hayashi, Kazunari Sasaki, Correlating cathode microstructure with PEFC performance using FIB-SEM and TEM, Journal of the Electrochemical Society, 10.1149/2.0581709jes, 164, 9, F928-F934, 2017.01, [URL], The cathode electrocatalyst layers of polymer electrolyte membrane fuel cells (PEFCs) are quantitatively investigated for different ratios of Nafion ionomer. This is achieved using focused-ion-beam coupled scanning electron microscopy (FIB-SEM) to reconstruct the three-dimensional microstructure via tomography. Parameters such as the porosity and pore size distribution were calculated from this data. The distributions of Nafion ionomer, carbon support, and platinum nanoparticles were then further clarified using transmission electron microscopy (TEM). Changes in the PEFC performance (notably the I-V characteristics, the electrochemical surface area, the activation overvoltage, and the concentration overvoltage) are thus correlated to electrode microstructure..
28. T. Bayer, R. Selyanchyn, Shigenori Fujikawa, Kazunari Sasaki, Stephen Matthew Lyth, Spray-painted graphene oxide membrane fuel cells, Journal of Membrane Science, 10.1016/j.memsci.2017.07.012, 541, 347-357, 2017.01, [URL], Graphene oxide (GO) is potentially a useful electrolyte material for polymer electrolyte membrane fuel cells due to its high strength, excellent hydrogen gas barrier properties, hydrophilicity, and proton conducting acidic functional groups. Here, GO paper is prepared from aqueous dispersion by vacuum-filtration, and the hydrogen permeability (2 × 10−2 barrer) is measured to be 3 orders of magnitude lower than Nafion (30 barrer) at 30 °C. The in-plane and through-plane conductivities are measured to be 49.9 and 0.3 mS cm−1, respectively. This significant anisotropy is attributed to the lamellar structure of GO, and the physical anisotropy between the thickness and lateral size of the GO nanoplatelets. Interestingly, the in-plane conductivity of GO is comparable to the through-plane conductivity of Nafion. GO membrane fuel cells (GOMFCs) are fabricated. To compensate for the low in-plane conductivity of GO, whilst taking advantage of the excellent hydrogen gas barrier properties, extremely thin electrode-supported GOMFCs are prepared by spray painting GO directly onto the electrocatalyst layer. The effect of membrane thickness on cell performance is investigated. Decreasing membrane thickness by spray painting improves the power density from 3.7 mW cm−2 for a 50 μm-thick membrane-supported GOMFC, to 79 mW cm−2 for a 3 µm-thick, spray-painted membrane, electrode-supported GOMFC..
29. Huei Ru Molly Jhong, Claire E. Tornow, Bretislav Smid, Andrew A. Gewirth, Stephen Matthew Lyth, Paul J.A. Kenis, A Nitrogen-Doped Carbon Catalyst for Electrochemical CO2 Conversion to CO with High Selectivity and Current Density, ChemSusChem, 10.1002/cssc.201600843, 10, 6, 1094-1099, 2017, [URL], We report characterization of a non-precious metal-free catalyst for the electrochemical reduction of CO2 to CO; namely, a pyrolyzed carbon nitride and multiwall carbon nanotube composite. This catalyst exhibits a high selectivity for production of CO over H2 (approximately 98 % CO and 2 % H2), as well as high activity in an electrochemical flow cell. The CO partial current density at intermediate cathode potentials (V=−1.46 V vs. Ag/AgCl) is up to 3.5× higher than state-of-the-art Ag nanoparticle-based catalysts, and the maximum current density is 90 mA cm−2. The mass activity and energy efficiency (up to 48 %) were also higher than the Ag nanoparticle reference. Moving away from precious metal catalysts without sacrificing activity or selectivity may significantly enhance the prospects of electrochemical CO2 reduction as an approach to reduce atmospheric CO2 emissions or as a method for load-leveling in relation to the use of intermittent renewable energy sources..
30. Jianfeng Liu, Benjamin V. Cunning, Takeshi Daio, Albert Mufundirwa, Kazunari Sasaki, Stephen Matthew Lyth, Nitrogen-Doped Carbon Foam as a Highly Durable Metal-Free Electrocatalyst for the Oxygen Reduction Reaction in Alkaline Solution, Electrochimica Acta, 10.1016/j.electacta.2016.10.090, 220, 2016.12, [URL], Nitrogen-doped carbon foam (CFN) with large surface area is synthesized via a template-free, scalable combustion technique using diethanolamine as a nitrogen source. The resulting macroporous, open-cell foam has micron-scale hollow cells, surrounded by thin, graphene-like walls. This material is applied as a metal-free electrocatalyst for the oxygen reduction reaction (ORR) in alkaline KOH solution. The activity of this metal-free electrocatalyst at the half-wave potential is just 43 mV lower than that of platinum-decorated carbon (Pt/CB), but 87 mV lower than a commercially available Fe-containing non-precious electrocatalyst (Pajarito Powder, PP), suggesting that iron is important in achieving the highest activities. In durability tests measured over 60,000 potential cycles, Pt/CB and PP undergo significant degradation, whilst the non-precious CFN electrocatalyst shows negligible change, indicating high stability of the electrochemical active sites compared with platinum or iron. Such metal-free catalysts therefore show great promise as electrocatalysts for specific alkaline ion exchange membrane fuel cell (AEMFC) applications where long lifetimes are most important..
31. Prabakaran Saravanan, Roman Selyanchyn, Hiroyoshi Tanaka, Durgesh Darekar, Aleksandar Tsekov Staykov, Shigenori Fujikawa, Stephen Matthew Lyth, Joichi Sugimura, Macroscale Superlubricity of Multilayer Polyethylenimine/Graphene Oxide Coatings in Different Gas Environments, ACS applied materials & interfaces, 10.1021/acsami.6b06779, 8, 40, 27179-27187, 2016.10, [URL], Friction and wear decrease the efficiency and lifetimes of mechanical devices. Solving this problem will potentially lead to a significant reduction in global energy consumption. We show that multilayer polyethylenimine/graphene oxide thin films, prepared via a highly scalable layer-by-layer (LbL) deposition technique, can be used as solid lubricants. The tribological properties are investigated in air, under vacuum, in hydrogen, and in nitrogen gas environments. In all cases the coefficient of friction (COF) significantly decreased after application of the coating, and the wear life was enhanced by increasing the film thickness. The COF was lower in dry environments than in more humid environments, in contrast to traditional graphite and diamond-like carbon films. Superlubricity (COF < 0.01) was achieved for the thickest films in dry N2. Microstructural analysis of the wear debris revealed that carbon nanoparticles were formed exclusively in dry conditions (i.e., N2, vacuum), and it is postulated that these act as rolling asperities, decreasing the contact area and the COF. Density functional theory (DFT) simulations were performed on graphene oxide sheets under pressure, showing that strong hydrogen bonding occurs in the presence of intercalated water molecules compared with weak repulsion in the absence of water. It is suggested that this mechanism prevents the separation graphene oxide layers and subsequent formation of nanostructures in humid conditions..
32. Thomas Bayer, Hung Cuong Pham, Kazunari Sasaki, Stephen Matthew Lyth, Spray deposition of Nafion membranes
Electrode-supported fuel cells, Journal of Power Sources, 10.1016/j.jpowsour.2016.07.059, 327, 319-326, 2016.09, [URL], Fuel cells are a key technology for the successful transition towards a hydrogen society. In order to accelerate fuel cell commercialization, improvements in performance are required. Generally, polymer electrolyte membrane fuel cells (PEFCs) are membrane-supported; the electrocatalyst layer is sprayed onto both sides of the membrane, and sandwiched between carbon-based gas diffusion layers (GDLs). In this work we redesign the membrane electrode assembly (MEA) and fabricate an electrode-supported PEFC. First the electrocatalyst layer is sprayed onto the GDL, and then Nafion dispersion is sprayed over the top of this to form a thin membrane. This method has the advantage of simplifying the fabrication process, allowing the fabrication of extremely thin electrolyte layers (down to ∼10 μm in this case), and reducing the amount of ionomer required in the cell. Electrode-supported PEFCs operate at significantly increased power density compared to conventional membrane-supported PEFCs, with a maximum of 581 mW/cm2 at 80 °C (atmospheric pressure, air at the cathode). Impedance spectroscopy confirmed that the origin of the improved performance was an 80% reduction in the membrane resistance due the thinner Nafion layer. This novel fabrication method is a step towards cheaper, thinner, fully printable PEFCs with high power density and efficiency..
33. Takeshi Daio, Pratoy Mitra, Stephen Matthew Lyth, Kazunari Sasaki, Atomic-resolution analysis of degradation phenomena in SOFCS
A case study of SO2 poisoning in LSM cathodes, International Journal of Hydrogen Energy, 10.1016/j.ijhydene.2016.05.216, 41, 28, 12214-12221, 2016.07, [URL], Solid oxide fuel cell (SOFC) degradation studies are often performed by scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). However, it is difficult to use these techniques to observe processes occurring at the smallest scales. Here, we study sulfur poisoning of La0.8Sr0.2MnO3−δ (LSM) cathodes as a model case for atomic resolution scanning transmission electron microscopy (STEM) analysis with energy dispersive X-ray diffraction (EDX). Significant SrSO4 nanoparticle formation is observed after SO2 exposure, especially at grain boundaries in the LSM. In addition, La2O3 formation inside the grain was also confirmed. The formation of SrSO4 is identified with irreversible SOFC degradation, in addition to simple SO2 adsorption, which is reversible..
34. Thomas Bayer, Benjamin V. Cunning, Roman Selyanchyn, Masamichi Nishihara, Shigenori Fujikawa, Kazunari Sasaki, Stephen Matthew Lyth, High temperature proton conduction in nanocellulose membranes
Paper fuel cells, Chemistry of Materials, 10.1021/acs.chemmater.6b01990, 28, 13, 4805-4814, 2016.07, [URL], Polymer electrolyte membrane fuel cells are an efficient and clean alternative power source, but high cost impedes widespread commercialization. The fuel cell membrane, e.g., Nafion, contributes significantly to this cost, and therefore, novel alternatives are required. Temperature is also an important factor; high temperature operation leads to faster reaction kinetics, lower electrocatalyst loading, and improved water management, thereby further reducing cost. However, higher temperature puts greater demands on the membrane. Conductivity is related strongly to humidification, and therefore, this generally decreases above 100 °C. Nanocellulose membranes for fuel cells in which the proton conductivity increases up to 120 °C are reported here for the first time. The hydrogen barrier properties are far superior to conventional ionomer membranes. Fuel cells with nanocellulose membranes are successfully operated at 80 °C. Additionally, these membranes are environmentally friendly and biodegradable..
35. Thomas Bayer, Benjamin V. Cunning, Roman Selyanchyn, Takeshi Daio, Masamichi Nishihara, Shigenori Fujikawa, Kazunari Sasaki, Stephen Matthew Lyth, Alkaline anion exchange membranes based on KOH-treated multilayer graphene oxide, Journal of Membrane Science, 10.1016/j.memsci.2016.02.017, 508, 51-61, 2016.06, [URL], A novel class of alkaline anion exchange membrane (AAEM) is presented, in the form of KOH-modified multilayer graphene oxide paper (GOKOH). Such membranes can be easily fabricated at large scale with varying thickness using conventional filtration techniques, and have high tensile strength (24.5 MPa). However, a large degree of swelling is observed. SEM investigations show that the morphology of GO changes after KOH-treatment, whilst XPS measurements and XRD analysis confirm successful chemical modification. The hydrogen gas permeability is several orders of magnitude lower than conventional polymer-based ionomer membranes. The maximum anion conductivity is 6.1 mS/cm at 70 °C, and the dominant charge carrier is confirmed to be OH- by utilization of anion and proton-conducting blocking layers. The ion exchange capacity is 6.1 mmol/g, measured by titration. A water-mediated reverse Grotthuss-like mechanism is proposed as the main diffusion mode of OH- ions. Finally, a prototype AAEM fuel cell is fabricated using a GOKOH membrane, confirming the applicability to real systems..
36. Thomas Bayer, Sean R. Bishop, Nicola H. Perry, Kazunari Sasaki, Stephen Matthew Lyth, Tunable Mixed Ionic/Electronic Conductivity and Permittivity of Graphene Oxide Paper for Electrochemical Energy Conversion, ACS applied materials & interfaces, 10.1021/acsami.6b01670, 8, 18, 11466-11475, 2016.05, [URL], Graphene oxide (GO) is a two-dimensional graphitic carbon material functionalized with oxygen-containing surface functional groups. The material is of interest in energy conversion, sensing, chemical processing, gas barrier, and electronics applications. Multilayer GO paper has recently been applied as a new proton conducting membrane in low temperature fuel cells. However, a detailed understanding of the electrical/dielectric properties, including separation of the ionic vs electronic contributions under relevant operating conditions, has so far been lacking. Here, the electrical conductivity and dielectric permittivity of GO paper are investigated in situ from 30 to 120 °C, and from 0 to 100% relative humidity (RH) using impedance spectroscopy. These are related to the water content, measured by thermogravimetric analysis. With the aid of electron blocking measurements, GO is demonstrated to be a mixed electronic-protonic conductor, and the ion transference number is derived for the first time. For RH > 40%, conductivity is dominated by proton transport (with a maximum of 0.5 mS/cm at 90 °C and 100% RH). For RH < 40%, electronic conductivity dominates (with a maximum of 7.4 mS/cm at ∼80 °C and 0% RH). The relative permittivity of GO paper increases with decreasing humidity, from ∼10 at 100% RH to several 1000 at 10% RH. These results underline the potential of GO for application not only as a proton conducting electrolyte but also as a mixed conducting electrode material under appropriate conditions. Such materials are highly applicable in electrochemical energy conversion and storage devices such as fuel cells and electrolyzers..
37. Jet Sing M. Lee, Gary Rochelle, Peter Styring, Paul Fennell, Grant Wilson, Martin Trusler, Peter Clough, John Blamey, Matthew Dunstan, Niall Macdowell, Stephen Matthew Lyth, Joseph Yao, Thomas Hills, Matteo Gazzani, Patrick Brandl, Rahul Anantharaman, Stefano Brandani, Joshuah Stolaroff, Marco Mazzotti, Geoffrey Maitland, Christoph Müller, George Dowson, Jon Gibbins, Raffaella Ocone, Kyra Sedransk Campbell, María Erans, Liya Zheng, Daniel Sutter, Andac Armutlulu, Berend Smit, CCS-A technology for now
General discussion, Faraday Discussions, 10.1039/c6fd90052f, 192, 125-151, 2016.01, [URL].
38. J. Liu, S. Yu, T. Daio, M. S. Ismail, Kazunari Sasaki, Stephen Matthew Lyth, Metal-free nitrogen-doped carbon foam electrocatalysts for the oxygen reduction reaction in acid solution, Journal of the Electrochemical Society, 10.1149/2.0631609jes, 163, 9, F1049-F1054, 2016.01, [URL], Metal-free, nitrogen-doped carbon foam is utilized as a model non-precious electrocatalyst system to investigate the role of nitrogen in the oxygen reduction reaction (ORR) in the absence of iron contamination. This graphene-like foam displays relatively high activity for the ORR in acid, despite being proven free from transition-metal impurities. The onset potential is 0.85 VRHE, the mass activity is 2.8 A/g at 0.6 VRHE, and the current density is -4.0 mA/cm2. The maximum electron transfer number is calculated to be 3.6, revealing that a 4-electron pathway is possible in nitrogen-doped carbon, even in the absence of transition-metal coordination sites. The excellent electrochemical activity is attributed to the large surface area (700 m2/g), improved conductivity after graphitization, and the relatively high proportion of tertiary (graphite-like) nitrogen..
39. Berend Smit, Peter Styring, Grant Wilson, Gary Rochelle, Felix Donat, Joseph Yao, Martin Trusler, Claire Adjiman, Stephen Matthew Lyth, Jet Sing M. Lee, Thomas Hills, Patrick Brandl, Matteo Gazzani, Rosa Cuellar-Franca, Paul Fennell, Daniel Sutter, Mai Bui, Colin Scholes, George Dowson, Jon Gibbins, Lisa Joss, Geoffrey Maitland, Stefano Brandani, Pelayo Garcia-Gutierrez, Yue Zhang, Christoph Müller, George Jackson, Raffaella Ocone, Lennart Joos, Robert Bell, Richard Graham, Modelling-from molecules to mega-scale
General discussion, Faraday Discussions, 10.1039/C6FD90054B, 192, 493-509, 2016.01, [URL].
40. Takeshi Daio, Aleksandar Tsekov Staykov, Limin Guo, Jianfeng Liu, Masaki Tanaka, Stephen Matthew Lyth, Kazunari Sasaki, Lattice Strain Mapping of Platinum Nanoparticles on Carbon and SnO 2 Supports, Scientific Reports, 10.1038/srep13126, 5, 2015.08, [URL], It is extremely important to understand the properties of supported metal nanoparticles at the atomic scale. In particular, visualizing the interaction between nanoparticle and support, as well as the strain distribution within the particle is highly desirable. Lattice strain can affect catalytic activity, and therefore strain engineering via e.g. synthesis of core-shell nanoparticles or compositional segregation has been intensively studied. However, substrate-induced lattice strain has yet to be visualized directly. In this study, platinum nanoparticles decorated on graphitized carbon or tin oxide supports are investigated using spherical aberration-corrected scanning transmission electron microscopy (Cs-corrected STEM) coupled with geometric phase analysis (GPA). Local changes in lattice parameter are observed within the Pt nanoparticles and the strain distribution is mapped. This reveals that Pt nanoparticles on SnO 2 are more highly strained than on carbon, especially in the region of atomic steps in the SnO 2 lattice. These substrate-induced strain effects are also reproduced in density functional theory simulations, and related to catalytic oxygen reduction reaction activity. This study suggests that tailoring the catalytic activity of electrocatalyst nanoparticles via the strong metal-support interaction (SMSI) is possible. This technique also provides an experimental platform for improving our understanding of nanoparticles at the atomic scale..
41. Angus Cook, Gerald Frankel, Alison Davenport, Trevor Hughes, Simon Gibbon, David Williams, Hendrik Bluhm, Vincent Maurice, Stephen Matthew Lyth, Philippe Marcus, David Shoesmith, Clara Wren, Julian Wharton, Gregory Hunt, Stuart Lyon, Tom Majchrowski, Rob Lindsay, Geraint Williams, Beatriz Rico Oller, Mira Todorova, Sonja Nixon, Su Ting Cheng, John Scully, Ann Wilson, Frank Renner, Ying Hsuan Chen, Christopher Taylor, Hiroki Habazaki, Angelos Michaelides, Suzanne Morsch, Peter Visser, Line Kyhl, Anton Kokalj, Corrosion control
General discussion, Faraday Discussions, 10.1039/c5fd90047f, 180, 543-576, 2015.01, [URL].
42. Yuya Tachikawa, J. Sugimoto, M. Takada, T. Kawabata, Stephen Matthew Lyth, Yusuke Shiratori, Kazunari Sasaki, In operando visualization of SOFC electrodes by thermography and visible light imaging, ECS Electrochemistry Letters, 10.1149/2.0031511eel, 4, 11, F61-F64, 2015.01, [URL], The temperature distribution in internal reforming SOFC anodes can be visualized by thermography. However, thermal imaging techniques are limited since they cannot take into account the influence of emissivity changes caused by carbon deposition on the anode. This problem can be solved by simultaneous visualization using thermography and visible light imaging. By combining these techniques, carbon deposition can be monitored via visible light imaging, whilst temperature changes due to the reforming reaction can be monitored by thermal imaging. This in operando visualization technique enables the evaluation and prediction of the distribution of multiple chemical reactions on the SOFC electrodes..
43. Janine Mauzeroll, Geoffrey Thornton, Trevor Rayment, Vincent Maurice, David Williams, Frank Heberling, Philippe Marcus, Clara Wren, Kirsi Yliniemi, Rob Lindsay, Stephen Matthew Lyth, Tom Majchrowski, Hadeel Hussain, Gregory Hunt, Frank Renner, Geraint Williams, Roger Newman, Gerald Frankel, Johannes Lützenkirchen, Hendrik Bluhm, Solid/fluid interface
General discussion, Faraday Discussions, 10.1039/c5fd90044a, 180, 81-96, 2015.01, [URL].
44. Stephen Matthew Lyth, W. Ma, J. Liu, T. Daio, Kazunari Sasaki, Atsushi Takahara, B. Ameduri, Solvothermal synthesis of superhydrophobic hollow carbon nanoparticles from a fluorinated alcohol, Nanoscale, 10.1039/c5nr03484a, 7, 38, 16087-16093, 2015.01, [URL], A new and simple method of synthesizing fluorinated carbon at the gram scale is presented by reacting a fluorinated alcohol with sodium at elevated temperatures in a sealed Teflon reactor. The resulting carbon nanoparticles are around 100 nm in diameter, and display a hollow shell morphology, with a significant amount of fluorine doped into the carbon. The nanoparticles disperse easily in ethanol, and are thermally stable up to 400°C and 450°C under air and nitrogen, respectively. The nanoparticle dispersion was printed onto various substrates (paper, cloth, silicon), inducing superhydrophobicity..
45. Takeshi Daio, Haiwen Li, Takashi Gondo, Hiroya Miyazaki, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata, Stephen Matthew Lyth, Kazunari Sasaki, Dynamic Gas Environmental System Development for in situ Real-time SEM Imaging under Atmospheric Pressure, Microscopy and Microanalysis, 10.1017/S1431927615009289, 21, 1701-1702, 2015, [URL].
46. Stephen Matthew Lyth, S. R P Silva, Electron field emission from water-based carbon nanotube inks, ECS Journal of Solid State Science and Technology, 10.1149/2.0051504jss, 4, 4, P3034-P3043, 2015, [URL], Printable electron field emitters could lead to cheap and scalable large area electron sources. This paper presents work on electron field emission from water-based multiwall carbon nanotube (MWCNT) dispersions, and introduces new results on emission from different substrates. We summarize work in which MWCNTs are deposited onto paper, glass, and plastic substrates, and show that the field emission characteristics can be tailored by controlling the underlying morphology as well as by post-laser irradiation. We also show that engineering the work function of MWCNTs can significantly enhance field emission, and that resonant tunneling effects may be induced by suitable surface functionalization..
47. T. Bayer, S. R. Bishop, Masamichi Nishihara, Kazunari Sasaki, Stephen Matthew Lyth, Characterization of a graphene oxide membrane fuel cell, Journal of Power Sources, 10.1016/j.jpowsour.2014.08.071, 272, 239-247, 2014.12, [URL], The electrical, mechanical, and compositional characterization of a graphene oxide membrane is presented, and its application as an electrolyte material in a polymer electrolyte membrane fuel cell is explored. Self-supporting graphene oxide membranes were prepared by a simple vacuum filtration process and, for the first time, characterized as the electrolyte in a fuel cell operating in an elevated temperature range (30-80 °C), with a maximum power density of ∼34 mW cm-2, approaching that of a Nafion electrolyte based cell prepared and tested under similar conditions. Evidence for partial membrane reduction was found at higher temperatures and is believed to originate from more easily released, higher energy oxide groups, such as epoxides. We also discuss the morphology, the mechanical properties, chemical composition, and electrical conductivity of the graphene oxide membranes, with comparisons made to conventional Nafion membranes..
48. J. Liu, D. Takeshi, Kazunari Sasaki, Stephen Matthew Lyth, Platinum-Decorated Nitrogen-Doped Graphene Foam Electrocatalysts, Fuel Cells, 10.1002/fuce.201300258, 14, 5, 728-734, 2014.10, [URL], Large-scale, facile synthesis of nitrogen-doped graphene foam (GF) from low cost precursors is reported as a support material for platinum in fuel cell cathodes. The nitrogen-doped GF was produced by combustion of nitrogen-containing sodium alkoxide, followed by washing and heat treatment in various gases. A nitrogen-free reference sample was also synthesized. The BET surface area is higher than 700 m2 g-1, and the material is highly defective, partly due to the inclusion of nitrogen, and partly due to the low temperature, catalyst-free synthesis method. These defects result in an excellent distribution of platinum nanoparticles on the surface. The electrochemical performance of the resulting electrocatalysts was characterized using cyclic voltammetry and linear sweep voltammetry, revealing that nitrogen doping has potential to increase the durability of graphene-based catalysts. Therefore, this material is a potentially useful catalyst support for use in polymer electrolyte membrane fuel cells..
49. Y. Takabatake, Z. Noda, Stephen Matthew Lyth, Akari Hayashi, Kazunari Sasaki, Cycle durability of metal oxide supports for PEFC electrocatalysts, International Journal of Hydrogen Energy, 10.1016/j.ijhydene.2014.01.094, 39, 10, 5074-5082, 2014.03, [URL], In order to develop durable electrocatalysts for polymer electrolyte fuel cells, six different metal oxides, namely MoO3, SnO2, Nb2O5, Ta2O5, TiO2, and WO3, are selected as thermochemically stable, carbon-free platinum electrocatalyst support materials. The stability of Pt on these alternative oxide support materials is systematically analyzed, for the first time, using common experimental protocols simulating realistic fuel cell vehicle operation. Pt/SnO2 shows the best performance in terms of both electrochemical activity, and stability against dissolution. Pt dissolution rates in Pt/SnO 2 are comparable to those of conventional Pt/C electrocatalysts. These results suggest that SnO2 is a promising candidate as an alternative electrocatalyst support..
50. Yury Gogotsi, Richard McCreery, Stephen Matthew Lyth, Robert Dryfe, John Foord, Matěj Velický, Julie Macpherson, Matteo Duca, Katherine Holt, Manuel Alvarez-Guerra, Heisi Kurig, Surbhi Sharma, Patrick R. Unwin, George Zheng Chen, Milo Shaffer, Taiwo Alaje, Robert Hamers, Mark Newton, Philip A. Ash, Keith Stevenson, Siegfried Waldvogel, Jingping Hu, Aleix Güell, Jonathan Quinson, Carbon electrode interfaces for synthesis, sensing and electrocatalysis
General discussion, Faraday Discussions, 10.1039/C4FD90038C, 172, 497-520, 2014.01, [URL].
51. Jianfeng Liu, Daio Takeshi, Daniel Mantecon Orejon, A. Kazunari Sasaki, Stephen Matthew Lyth, Defective nitrogen-doped graphene foam
A metal-free, non-precious electrocatalyst for the oxygen reduction reaction in acid, Journal of the Electrochemical Society, 10.1149/2.095404jes], 161, 4, F544-F550, 2014.01, [URL], Platinum-free oxygen reduction reaction (ORR) catalysts could help reduce the cost of future generations of polymer electrolyte membrane fuel cells (PEFCs). One class of non-precious catalyst for PEFCs are nanostructured Fe/C/N-based materials. In these, the nature of the active site is still hotly contested. Resolving this issue could lead to the development of better catalysts. One approach to achieve this is to study nitrogen-doped carbons, without any Fe content. Such materials have been studied, but largely in alkaline media where high activity is routinely obtained. Studies of metal-free catalysts in acid are rare, and Fe-contamination is often an issue. To truly shed light on the ORR mechanism of Fe/C/N-based catalysts, measurements on metal-free catalysts in acid media are required to simulate proton-based PEFC systems. Here we present synthesis of a metal-free defective nitrogen-doped graphene powder with remarkable surface area. We apply this as an ORR catalyst in acid medium and comment on the reaction mechanism..
52. Stephen Matthew Lyth, Huaiyu Shao, Jianfeng Liu, Kazunari Sasaki, Etsuo Akiba, Hydrogen adsorption on graphene foam synthesized by combustion of sodium ethoxide, International Journal of Hydrogen Energy, 10.1016/j.ijhydene.2013.10.044, 39, 1, 376-380, 2014.01, [URL], Hydrogen storage is a crucial technology for the realization of a carbon-neutral society. However, few materials have been able to approach useful hydrogen storage capacity at reasonable temperatures and pressures. Graphene has an extremely high surface-area-to-weight ratio, is strong, cheap, chemically inert, and environmentally benign. As such it may be an ideal substrate for hydrogen storage. Here we present synthesis of graphene foam by combustion of sodium ethoxide. This technique is low-cost, scalable, and results in a three-dimensional graphene network with a surface area of more than 1200 m 2/g. It is applied as a hydrogen storage material at liquid nitrogen temperature, with a capacity of 2.1 wt%..
53. T. Tsukatsune, Y. Takabatake, Z. Noda, T. Daio, A. Zaitsu, Stephen Matthew Lyth, Akari Hayashi, Kazunari Sasaki, Platinum-decorated tin oxide and niobium-doped tin oxide pefc electrocatalysts
Oxygen reduction reaction activity, Journal of the Electrochemical Society, 10.1149/2.0431412jes, 161, 12, F1208-F1213, 2014.01, [URL], Using tin oxide (SnO2) and niobium-doped tin oxide (Nb-SnO2) as alternative electrocatalyst support materials can effectively solve the issue of carbon corrosion in polymer electrolyte fuel cell (PEFC) cathodes. Here, we systematically explore the effect of support surface area, Pt loading, and Pt nanoparticle size on the electrochemistry of these carbon-free electrocatalysts. Reducing the Pt loading leads to an increase in electrochemical surface area, but the specific activity decreases as previously observed in conventional carbon based electrocatalysts. Removing residual chlorine impurities by replacing the H2PtCl6 nanoparticle precursor with Pt(acac)2 increases the specific activity. Niobium-doping of the SnO2 support also results in an increase in specific activity, due to the increased electronic conductivity. Consequently, the oxygen reduction reaction activity of optimized Pt-decorated Nb-SnO2 is approaching to that of Pt-decorated carbon black, the current state-of-the-art PEFC electrocatalyst..
54. Jianfeng Liu, Daio Takeshi, Kazunari Sasaki, Stephen Matthew Lyth, Defective graphene foam
A platinum catalyst support for PEMFCs, Journal of the Electrochemical Society, 10.1149/2.0231409jes, 161, 9, 2014, [URL], Gram-scale synthesis of defective graphene foam from low-cost precursors is reported as a catalyst support material for platinum in fuel cell cathodes. The material was produced by combustion of sodium ethoxide, followed by washing and heat-treatment in various gases. The BET surface area is higher than 1500 m2/g. The defects in the material result in excellent distribution of platinum nanoparticles on the surface. The electrochemical performance is compared with platinum-decorated carbon black and commercially obtainable graphene using cyclic voltammetry, linear sweep voltammetry, andmembrane electrode assemblies. Pt-decorated grapheme foam has larger electrochemical surface area (101 m2/g) and higher mass activity (176 A/gPt). However, durability and fuel cell power density still require improvements. This graphene foam is a potentially useful catalyst support, especially for use in polymer electrolyte membrane fuel cells..
55. K. Kanda, Z. Noda, Y. Nagamatsu, T. Higashi, Shunsuke Taniguchi, Stephen Matthew Lyth, Akari Hayashi, Kazunari Sasaki, Negligible start-stop-cycle degradation in a PEFC utilizing platinum-decorated tin oxide electrocatalyst layers with carbon fiber filler, ECS Electrochemistry Letters, 10.1149/2.005404eel, 3, 4, 2014, [URL], Niobium-doped SnO2 is selected as an alternative carbon-free support material to negate carbon corrosion in polymer electrolyte fuel cells (PEFCs) electrocatalysts. The durability is measured using a membrane electrode assembly (MEA) over 60,000 start-stop cycles at high potential, equating to the lifetime of fuel cell vehicles. Using the Nb-doped SnO2 support results in retention of 99% of the initial cell voltage. The current-voltage characteristics are improved by adding carbon nanofibers as fillers in the Nb-doped SnO2, indicating that electronic conduction in the electrocatalyst layer is critical in the application ofmetal oxide-supported electrocatalysts..
56. M. Hanasaki, C. Uryu, T. Daio, T. Kawabata, Yuya Tachikawa, Stephen Matthew Lyth, Yusuke Shiratori, Shunsuke Taniguchi, Kazunari Sasaki, SOFC durability against standby and shutdown cycling, Journal of the Electrochemical Society, 10.1149/2.0421409jes, 161, 9, 2014, [URL], To simulate realistic operating conditions in SOFC systems, we investigate the influence of thermal cycling on the performance of electrolyte-supported planar SOFCs. Thermal cycling is often associated with interruption of fuel supply, with three main modes; hot standby, cold standby, and shutdown. Cell performance degradation is most significant during shutdown cycles. Nickel oxidation and agglomeration are more pronounced when SOFCs are subjected to lower temperatures for longer periods of time, leading to significant performance degradation. Ostwald ripening at the anode leads to degradation as Ni grains increase in size with cycling. Ni particle precipitation on the anode zirconia grains and along electrolyte grain boundaries is found for the first time in shutdown cycling tests. When H2S is mixed with the fuel, the internal reforming reactions and electrode reactions are inhibited by sulfur poisoning of the Ni anodes, accelerating degradation. The SOFC cycling degradation mechanisms are discussed in detail..
57. Jianfeng Liu, Kazunari Sasaki, Stephen Matthew Lyth, Electrochemical oxygen reduction on metal-free nitrogen-doped graphene foam in acidic media, Quaternary International, 10.1149/05801.1529ecst, 58, 1, 1529-1540, 2013, [URL], Non-precious oxygen reduction reaction (ORR) catalysts could help reduce the cost of future generations of polymer electrolyte membrane fuel cells (PEFCs). One class of Pt-free catalysts for PEFCs are nanostructured Fe/C/N-based materials. In these, the nature of the active site is still hotly contested. Resolving this issue could lead to the development of better catalysts. One approach to achieve this is to study nitrogen-doped carbons which do not contain any Fe. Such materials have been studied, but largely in alkaline media where high activity is obtained. To truly understand the ORR mechanism of Fe/C/N-based catalysts, measurements in acid media are required to simulate the activity in proton-based PEFC systems. Here we present bulk synthesis of a metal-free nitrogen-doped graphene powder with remarkable surface area. We apply this as an ORR catalyst in acid media and comment on the reaction mechanism..
58. Jianfeng Liu, Kazunari Sasaki, Stephen Matthew Lyth, Pt-decorated graphene-like foam for electrochemical oxygen reduction with high mass activity, Quaternary International, 10.1149/05801.1751ecst, 58, 1, 1751-1762, 2013, [URL], Gram-scale synthesis of graphene-like foam from low cost precursors is reported as a support material for platinum in fuel cell cathodes. The graphene-like foam was produced by combustion of sodium ethoxide, followed by washing and heat treatment in various gases. The BET surface area is higher than 1500 m2/g, although the material is highly defective. These defects result in an excellent distribution of platinum nanoparticles on the surface. The electrochemical performance of the resulting electrocatalysts are characterized using cyclic voltammetry and linear sweep voltammetry techniques, which reveal that this Pt-decorated graphene has large electrochemical surface area (101 m2/g) and high mass activity for the oxygen reduction reaction (176 A/gPt), making this graphene-like foam a potentially useful catalyst support for use in polymer electrolyte membrane fuel cells..
59. Stephen Matthew Lyth, Yuta Nabae, Nazrul Md Islam, Teruaki Hayakawa, Shigeki Kuroki, Masa Aki Kakimoto, Seizo Miyata, Solvothermal synthesis of nitrogen-containing graphene for electrochemical oxygen reduction in acid media, e-Journal of Surface Science and Nanotechnology, 10.1380/ejssnt.2012.29], 10, 29-32, 2012.03, [URL], Graphene is ideally suited to electrochemistry by virtue of its high surface area and impressive electronic properties. Nitrogen incorporation can be used to tailor the properties of graphene. Here we present a simple solvothermal technique to produce a nitrogen-containing foam-like macroporous graphene powder doped with up to 15 wt% nitrogen. This is applied as an effective non-precious, metal-free electrochemical catalyst for oxygen reduction in acid media..
60. Stephen Matthew Lyth, Y. Nabae, N. M. Islam, S. Kuroki, M. Kakimoto, S. Miyata, Oxygen reduction activity of carbon nitride supported on carbon nanotubes, Journal of Nanoscience and Nanotechnology, 10.1166/jnn.2012.4947, 12, 6, 4887-4891, 2012, [URL], Fuel cells offer an alternative to burning fossil fuels, but use platinum as a catalyst which is expensive and scarce. Cheap, alternative catalysts could enable fuel cells to become serious contenders in the green energy sector. One promising class of catalyst for electrochemical oxygen reduction is iron-containing, nanostructured, nitrogen-doped carbon. The catalytic activity of such N-doped carbons has improved vastly over the years bringing industrial applications ever closer. Stoichiometric carbon nitride powder has only been observed in recent years. It has nitrogen content up to 57% and as such is an extremely interesting material to work with. The electrochemical activity of carbon nitride has already been explored, confirming that iron is not a necessary ingredient for 4-electron oxygen reduction. Here, we synthesize carbon nitride on a carbon nanotube support and subject it to high temperature treatment in an effort to increase the surface area and conductivity. The results lend insight into the mechanism of oxygen reduction and show the potential for carbon nanotube-supported carbon nitride to be used as a catalyst to replace platinum in fuel cells..
61. Stephen Matthew Lyth, Y. Nabae, N. M. Islam, S. Kuroki, M. Kakimoto, S. Miyata, Electrochemical oxygen reduction activity of carbon nitride supported on carbon black, Journal of the Electrochemical Society, 10.1149/1.3519365, 158, 2, 2011, [URL], Electrochemical oxygen reduction via nonprecious, Fe/N/C catalysts has potential to reduce the cost and increase acceptance of hydrogen-powered polymer electrolyte membrane fuel cells. However, because these materials are a complex mixture of carbon, nitrogen, and iron, the nature of the active site is still much debated. By using carbon nitride as an ideal, nitrogen-rich, iron-free catalyst we shed light on the role of carbon-nitrogen bonding in electrochemical oxygen reduction. Carbon nitride was synthesized on a carbon black support via a simple solvothermal process. The resulting material was pyrolyzed and characterized via a variety of techniques. Electrochemical testing revealed that carbon nitride pyrolyzed at 1000°C displayed the best oxygen reduction activity, with an onset potential of 0.90 V and a low selectivity to H 2 O2 formation, indicating a 4-electron oxygen reduction pathway. Due to small amounts of Fe contamination in this series of samples, an Fe-free sample was prepared without the carbon black support, resulting in similar electrochemical properties. The enhanced activity is tentatively attributed to enriched quaternary nitrogen in the material at this temperature, as suggested by X-ray photoelectron spectroscopy..
62. Stephen Matthew Lyth, S. R.P. Silva, Resonant behavior observed in electron field emission from acid functionalized multiwall carbon nanotubes, Applied Physics Letters, 10.1063/1.3094755, 94, 12, 2009.04, [URL], Acid functionalized multiwall carbon nanotube ink was deposited onto carbon fiber fabric via dip coating. Repeatable staircaselike current-field curves were observed in the field emission data. These atypical curves are attributed to resonant tunneling through localized surface states in a quantum well structure, which arises due to the presence of the surface carboxylic functional group..
63. Stephen Matthew Lyth, S. J. Henley, S. R P Silva, Improved field emission via laser processing of carbon nanotubes on paper substrates, Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics, 10.1116/1.3123326, 27, 3, 1068-1071, 2009.01, [URL], The authors report excellent electron field emission characteristics from acid-oxidized multiwalled carbon nanotubes printed onto paper substrates and subjected to a postdeposition laser treatment. A distinct change in the morphology of the nanotube layer was observed after laser irradiation, and threshold fields improved from 4.8 V/μm before laser irradiation to 2.1 V/μm after laser irradiation. This study shows how field emission cathodes can be fabricated in a straightforward manner on cheap, flexible substrates and that the field emission characteristics can be tailored readily via postdeposition laser treatment..
64. Stephen Matthew Lyth, Yuta Nabae, Shogo Moriya, Shigeki Kuroki, Masa Aki Kakimoto, Jun Ichi Ozaki, Seizo Miyata, Carbon nitride as a nonprecious catalyst for electrochemical oxygen reduction, Journal of Physical Chemistry C, 10.1021/jp907928j, 113, 47, 20148-20151, 2009, [URL], Nitrogen-doped carbon-based catalysts are increasingly being studied as Pt-free electrodes for oxygen reduction in polymer electrolyte membrane fuel cells. Here, we study the oxygen reduction activity of stoichiometric carbon nitride, which has much higher nitrogen content and is synthesized at lower temperatures, without using ionic or metallic iron. Carbon nitride was studied and characterized via X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, BET specific surface area analysis, and thermogravimetric analysis. Rotating electrode voltammetry in oxygen-saturated sulfuric acid was used to determine the catalytic activity. The onset potential for oxygen reduction by carbon nitride electrodes was 0.69 V (vs NHE) compared to 0.45 V for a carbon black reference electrode. However, the current density was low, possibly due to the low surface area of the material. Blending the carbon nitride with a high surface area carbon black support resulted in a significant improvement in current density and in an increase in onset potential to 0.76 V. The role of surface area was elucidated via cyclic voltammetry. This work confirms that stoichiometric carbon nitride has improved inherent oxygen reduction activity compared to pure carbon, and suggests that Fe coordination sites are not essential for electrochemical oxygen reduction in nitrogen-containing carbon materials..
65. Paul C P Watts, Stephen Matthew Lyth, Simon J. Henley, S. Ravi P Silva, Secondary nanotube growth on aligned carbon nanofibre arrays for superior field emission, Journal of Nanoscience and Nanotechnology, 10.1166/jnn.2008.069, 8, 4, 2147-2150, 2008.04, [URL], We report substantial improvement of the field emission properties from aligned carbon nanotubes grown on aligned carbon nanofibres by a two-stage plasma enhanced chemical vapour deposition (PECVD) process. The threshold field decreased from 15.0 to 3.6 V/μm after the secondary growth. The field enhancement factor increased from 240 to 1480. This technique allows for superior emission of electrons for carbon nanotube/nanofibre arrays grown directly on highly doped silicon for direct integration in large area displays..
66. Stephen Matthew Lyth, S. R P Silva, Field emission from multiwall carbon nanotubes on paper substrates, Applied Physics Letters, 10.1063/1.2734379, 90, 17, 2007.05, [URL], The authors report extremely low electron field emission thresholds from acid oxidized multiwall carbon nanotubes deposited on paper substrates by dip coating in an aqueous nanotube ink. Using paper substrates of differing surface roughness, field emission threshold fields ranging from 0.8 to 11.6 Vμm were observed, varying in an approximate inverse linear log relationship with the surface roughness of the underlying paper substrate. This study shows how field emission from supported nanotube films can be tailored via the morphology of the scaffold substrate, and how these composite electrodes can be straightforwardly fabricated on cheap, flexible substrates..
67. Stephen Matthew Lyth, R. A. Hatton, S. R P Silva, Efficient field emission from Li-salt functionalized multiwall carbon nanotubes on flexible substrates, Applied Physics Letters, 10.1063/1.2430091, 90, 1, 2007, [URL], The authors report extremely low electron field emission thresholds of 0.25 Vμm from lithium salt functionalized multiwall carbon nanotubes adhered to carbon fiber fabric. Crucially, these nanostructured field emitters are flexible, air stable, and produced via a low cost dip-processing method using an aqueous nanotube ink, whereupon the nanotubes spontaneously assemble onto a surface oxidized carbon fiber matrix to form dense mats. The very low emission threshold is rationalized in terms of the morphology of the nanotube mats and the relatively low work function of lithium salt derivated carbon nanotubes..
68. Paul C P Watts, Stephen Matthew Lyth, Ernest Mendoza, S. Ravi P Silva, Polymer supported carbon nanotube arrays for field emission and sensor devices, Applied Physics Letters, 10.1063/1.2345615, 89, 10, 2006.09, [URL], The authors report a simple method for providing a polymer support structure for carbon nanotube (CNT) arrays for device applications. This method has a twofold effect: firstly it secures the nanotubes to the substrate and secondly it significantly decreases the threshold field for field emission from 26.2 to 9.7 V/ μm. This method ensures that the main body and tips of the CNTs are polymer-free and therefore can also be applied to CNT sensor array device fabrication..
69. Stephen Matthew Lyth, F. Oyeleye, R. J. Curry, J. Davis, S. R P Silva, Field emission from multiwall carbon nanotubes prepared by electrodeposition without the use of a dispersant, Journal of Vacuum Science & Technology B: Microelectronics Processing and Phenomena, 10.1116/1.2198855, 24, 3, 1362-1364, 2006.05, [URL], We present a technique of manufacturing multiwall carbon nanotube (MWNT) field emitters by a nickel electrodeposition process, without using a surfactant to disperse the MWNTs in solution. Sonication adequately disperses individual MWNTs throughout the solution and MWNTs can be deposited onto a copper substrate. However, over time there is a reduction of the free MWNT concentration in solution and an associated change in the morphology of the deposit. The initial concentration of MWNTs in solution also plays a crucial role in the morphology of the deposits. The threshold field of electron field emission measurements remained in the order of 20 Vμm regardless of the deposition conditions..
70. S. R P Silva, N. Blanchard, Stephen Matthew Lyth, Nanotechnology
The science and engineering of tomorrow, Journal of the National Science Foundation of Sri Lanka, 34, 1, 3-5, 2006.03.
71. Jianfeng LIU, Kazunari SASAKI, Stephen Matthew LYTH, Pt-decorated Graphene-like Foam for Electrochemical Oxygen Reduction with High Mass Activity., ECS Transactions, 58, 1, 1751-1762, 2013.10.