九州大学 研究者情報
発表一覧
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


学会発表等
1. S. M. Lyth, Graphene Oxide Membranes for Fuel Cells, Graphene Oxide Study Group Symposium, Kumamoto University, 2020.11.
2. S. M. Lyth, In-Situ High-Temperature X-Ray Absorption Spectroscopy of Fe-N-C Electrocatalysts during Pyrolysis, Electrochemical Society, 2020.10.
3. M. I. M. Kusdhany, H. W. Li, A. Mufundirwa, K. Sasaki, A. Hayashi, and S. M. Lyth, Hydrogen Storage on Nanoporous Carbon Foam for Electrochemical Applications, Electrochemical Society, 2020.10.
4. S. Suzuki, A. Mufundirwa, K. Sasaki, A. Hayashi, and S. M. Lyth, Alternative Me-N-C Based Carbon Foams as Fe-Free and Non-PGM Electrocatalysts, Electrochemical Society, 2020.10.
5. , A. Mufundirwa, C. E. Gell, S. Yoshioka, T. Sugiyama, B. V. Cunning, B. Smid, G. F. Harrington, K. Sasaki, A. Hayashi, and S. M. Lyth, Elucidating the Formation Mechanisms of Fe-N-C Electrocatalysts Using High-Temperature in Situ Characterisation Techniques, Electrochemical Society, 2020.10.
6. F. C. Lee, M. S. Ismail, D. B. Ingham, K. J. Hughes, L. Ma, S. M. Lyth, and M. Pourkashanian, , An Assessment of Novel Graphene Foam and Graphene-Based Microporous Layers for Polymer Electrolyte Fuel Cells: Fabrication and Characterisation. , Electrochemical Society, 2020.10.
7. O. Selyanchyn, R. Selyanchyn, K. Sasaki and S. M. Lyth, Nanocellulose Crosslinked with Sulfonic Acid As an Alternative Proton Conductive Membrane for Hydrogen Fuel Cells, Electrochemical Society, 2020.10.
8. S. M. Lyth, Advanced Characterization of Fe-N-C Electrocatalysts for Fuel Cells, Royal Society of Chemistry Tokyo International Conference, 2019.09.
9. S. M. Lyth, Insights into the Pyrolysis of Fe-N-C Electrocatalysts using High Temperature XAFS, European Fuel Cell and Electrolysis Discussions (EFCD), , 2019.09.
10. S. M. Lyth, Advanced Characterization of Fe-N-C Electrocatalysts for Fuel Cells, The 60th Battery Symposium, 2019.11.
11. S. M. Lyth, Nanomaterials for Hydrogen Energy Systems , First UAE-Japan Hydrogen Workshop, Nanomaterials for Hydrogen Energy Systems Khalifa University, 2020.12.
12. Stephen Lyth, Designing Cheaper Fuel Cells: Towards a Safer Future, Jaffna University International Conference (JUICe2018), 2019.06.
13. Stephen Lyth, Reducing the Cost of Hydrogen Fuel Cells: Sooty Catalysts and Paper Membranes, 58th Battery Symposium in Japan, 2018.11.
14. Stephen Lyth, Paper Fuel Cells: Bringing the Hydrogen Economy to the Masses, European Innovation Day, 2018.10.
15. Stephen M. LYTH, Thomas BAYER, Benjamin V. CUNNING, Bretislav SMID, Roman SELYANCHYN, Shigenori FUJIKAWA, and Kazunari SASAKI, Nanocellulose Proton Conducting Membranes for Fuel Cells, 5th Global Conference on Polymer and Composite Materials (PCM 2018), 2018.04, Nanocellulose is a promising new ionomer membrane material for polymer electrolyte membrane fuel cells (PEFCs). It is the most abundant polymer in the world, making it much cheaper than conventional ionomer membranes such as Nafion or Aquivion. It I three times stronger, and has three orders of magnitude lower hydrogen permeability than Nafion. We investigated the proton conductivity and prepared the world’s first operational PEFCs with nanocellulose membranes.

In order to improve the proton conductivity, we prepared sulfonated nanocellulose. To take advantage of the low hydrogen permeability and high strength, we developed very thin membranes. Spray-painting was used to fabricate “paper fuel cells” with 8 µm-thick sulfonated nanocellulose membranes. This resulted in high current density (almost 1 A cm-2), and a maximum power density of 156 mW cm-2 (H2/air, 80°C, 95% RH, 0.1 MPa).

The cost of these spray-painted sulfonated nanocellulose membranes was calculated to be ~50 $/m2, which is much lower than e.g. Nafion. This work paves the way for the mass production of affordable, recyclable, and even disposable fuel cells..
16. Stephen Lyth, Engineered Heteroatom-doped Carbons for Sustainable Energy Applications in Fukuoka, 7th World Annual Congress of Nano Science & Technology, 2017.10.
17. 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, 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..
18. Stephen Lyth, Novel Carbon-based Materials for Fuel Cell Membranes and Electrocatalyst Layers, 5th Fuel Cell International Meeting , 2017.02.
19. Stephen Lyth, Heteroatom-doped Carbon for Electrochemistry, Japanese Swiss Energy Materials Workshop, 2016.03.
20. Stephen Lyth, Graphene Oxide Ionomer Membranes, Workshop on Ion Exchange Membranes for Energy Applications (EMEA2015), 2015.06.
21. J. Liu, Kazunari Sasaki, Stephen Matthew Lyth, Defective nitrogen-doped graphene foam
A non-precious electrocatalyst for the oxygen reduction reaction in alkaline medium, 14th Polymer Electrolyte Fuel Cell Symposium, PEFC 2014 - 226th ECS Meeting, 2014.10, The oxygen reduction reaction has faster kinetics in anion exchange membrane fuel cell, opening the possibility of using nonprecious materials as electrocatalysts. Therefore, defective nitrogen-doped graphene foam is applied as an electrocatalyst in alkaline medium. The large surface area and highly porous structure results in high oxygen reduction reaction activity in rotating ring-disk electrode measurements. During potential cycling tests, the nitrogen-doped graphene foam displayed comparable durability to a Pt/CB catalyst..
22. J. Liu, T. Daio, Kazunari Sasaki, Stephen Matthew Lyth, Defective nitrogen-doped graphene foam
Clarifying the role of nitrogen in non-precious ORR catalysts, 14th Polymer Electrolyte Fuel Cell Symposium, PEFC 2014 - 226th ECS Meeting, 2014.10, Iron-free, nitrogen-doped graphene foam is presented as a model electrocatalyst system for studying the role of nitrogen in the oxygen reduction reaction in non-precious Fe/N/C-based electrocatalysts. Due to the large surface area and high porosity, these electrocatalysts display high activity in rotating ring-disk electrode voltammetry measurements. The electron transfer number is as high as 3.6, despite the metal-free nature of this electrocatalyst. The sample with the highest activity has a significantly larger proportion of tertiary/graphite-like nitrogen, and therefore this is proposed as a 4-electron oxygen reduction active site in acid environment..
23. T. Bayer, S. R. Bishop, Masamichi Nishihara, Kazunari Sasaki, Stephen Matthew Lyth, Graphene oxide membrane fuel cells
Utilizing of a new class of ionic conductor, 14th Polymer Electrolyte Fuel Cell Symposium, PEFC 2014 - 226th ECS Meeting, 2014.10, The characterization and application of graphene oxide membranes as fuel cell electrolytes is explored and presented. Morphology, chemical composition, mechanical and electrochemical properties of vacuum-filtration prepared graphene oxide membranes and their performance as fuel cell electrolytes are discussed. Our graphene oxide membrane fuel cell (GOMFC) showed a maximum power density of ∼ 6 mW/cm2 at 30 °C. Power density exhibited a decrease with increasing temperature and operation time, possibly due to partial loss of oxygen through reduction, and a resulting decrease in water-mediated proton transport..
24. Stephen Lyth, Graphene Oxide Membrane Fuel Cells, Solid State Protonic Conductors (SSPC-17), 2014.09.
25. Kazunari Sasaki, Z. Noda, T. Tsukatsune, K. Kanda, Y. Takabatake, Y. Nagamatsu, T. Daio, Stephen Matthew Lyth, Akari Hayashi, Alternative oxide-supported PEFC electrocatalysts, 14th Polymer Electrolyte Fuel Cell Symposium, PEFC 2014 - 226th ECS Meeting, 2014.01, Possible alternative electrocatalyst support materials to the conventional carbon black have been examined. Among others, doped-SnO2 can be a promising support for Pt nanoparticles well connected to the oxide with a certain crystallographic orientation. Pt/doped SnO2 exhibits suitable voltage cycle durability, while further improvement in oxygen reduction reaction (ORR) activity is still desired..
26. Kazunari Sasaki, Z. Noda, T. Tsukatsune, K. Kanda, Y. Takabatake, Y. Nagamatsu, T. Daio, Stephen Matthew Lyth, Akari Hayashi, Alternative oxide-supported PEFC electrocatalysts, 14th Polymer Electrolyte Fuel Cell Symposium, PEFC 2014 - 226th ECS Meeting, 2014.01, [URL], Possible alternative electrocatalyst support materials to the conventional carbon black have been examined. Among others, doped-SnO2 can be a promising support for Pt nanoparticles well connected to the oxide with a certain crystallographic orientation. Pt/doped SnO2 exhibits suitable voltage cycle durability, while further improvement in oxygen reduction reaction (ORR) activity is still desired..
27. J. Liu, Kazunari Sasaki, Stephen Matthew Lyth, Defective nitrogen-doped graphene foam
A non-precious electrocatalyst for the oxygen reduction reaction in alkaline medium, 14th Polymer Electrolyte Fuel Cell Symposium, PEFC 2014 - 226th ECS Meeting, 2014.01, [URL], The oxygen reduction reaction has faster kinetics in anion exchange membrane fuel cell, opening the possibility of using nonprecious materials as electrocatalysts. Therefore, defective nitrogen-doped graphene foam is applied as an electrocatalyst in alkaline medium. The large surface area and highly porous structure results in high oxygen reduction reaction activity in rotating ring-disk electrode measurements. During potential cycling tests, the nitrogen-doped graphene foam displayed comparable durability to a Pt/CB catalyst..
28. J. Liu, T. Daio, Kazunari Sasaki, Stephen Matthew Lyth, Defective nitrogen-doped graphene foam
Clarifying the role of nitrogen in non-precious ORR catalysts, 14th Polymer Electrolyte Fuel Cell Symposium, PEFC 2014 - 226th ECS Meeting, 2014.01, [URL], Iron-free, nitrogen-doped graphene foam is presented as a model electrocatalyst system for studying the role of nitrogen in the oxygen reduction reaction in non-precious Fe/N/C-based electrocatalysts. Due to the large surface area and high porosity, these electrocatalysts display high activity in rotating ring-disk electrode voltammetry measurements. The electron transfer number is as high as 3.6, despite the metal-free nature of this electrocatalyst. The sample with the highest activity has a significantly larger proportion of tertiary/graphite-like nitrogen, and therefore this is proposed as a 4-electron oxygen reduction active site in acid environment..
29. T. Bayer, S. R. Bishop, Masamichi Nishihara, Kazunari Sasaki, Stephen Matthew Lyth, Graphene oxide membrane fuel cells
Utilizing of a new class of ionic conductor, 14th Polymer Electrolyte Fuel Cell Symposium, PEFC 2014 - 226th ECS Meeting, 2014.01, [URL], The characterization and application of graphene oxide membranes as fuel cell electrolytes is explored and presented. Morphology, chemical composition, mechanical and electrochemical properties of vacuum-filtration prepared graphene oxide membranes and their performance as fuel cell electrolytes are discussed. Our graphene oxide membrane fuel cell (GOMFC) showed a maximum power density of ∼ 6 mW/cm2 at 30 °C. Power density exhibited a decrease with increasing temperature and operation time, possibly due to partial loss of oxygen through reduction, and a resulting decrease in water-mediated proton transport..
30. Stephen Lyth, Graphene Foam Electrocatalyst Supports, International Conference on Processing and Manufacturing of Advanced Materials (THERMEC), 2013.12.
31. Stephen Matthew Lyth, Jianfeng Liu, Kazunari Sasaki, Electrochemical oxygen reduction on nitrogen-containing graphene, 2012 12th IEEE International Conference on Nanotechnology, NANO 2012, 2012.11, [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..
32. Stephen Lyth, Electrochemistry on Graphene Nanofoam, PHOENICS International Symposium, 2012.03.
33. Stephen Matthew Lyth, Jianfeng Liu, Kazunari Sasaki, Electrochemical oxygen reduction on nitrogen-containing graphene, 2012 12th IEEE International Conference on Nanotechnology, NANO 2012, 2012, 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..
34. Stephen Matthew Lyth, Y. Nabae, N. M. Islam, S. Kuroki, M. Kakimoto, J. Ozaki, S. Miyata, Electrochemical oxygen reduction on carbon nitride, Electrode Processes Relevant to Fuel Cell Technology - 217th ECS Meeting, 2010.12, Electrochemical oxygen reduction via non-precious, Fe-macrocycle-derived catalysts has potential to reduce the cost and increase acceptance of hydrogen-powered polymer electrolyte membrane fuel cells. However since 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 0.90V and a low selectivity to H2O2 formation, indicating a 4-electron oxygen reduction pathway. The enhanced activity is attributed to enriched quaternary nitrogen in the material at this temperature, as confirmed by X-ray photoelectron spectroscopy..
35. Stephen Matthew Lyth, Y. Nabae, N. M. Islam, S. Kuroki, M. Kakimoto, J. Ozaki, S. Miyata, Electrochemical oxygen reduction on carbon nitride, Electrode Processes Relevant to Fuel Cell Technology - 217th ECS Meeting, 2010.12, [URL], Electrochemical oxygen reduction via non-precious, Fe-macrocycle-derived catalysts has potential to reduce the cost and increase acceptance of hydrogen-powered polymer electrolyte membrane fuel cells. However since 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 0.90V and a low selectivity to H2O2 formation, indicating a 4-electron oxygen reduction pathway. The enhanced activity is attributed to enriched quaternary nitrogen in the material at this temperature, as confirmed by X-ray photoelectron spectroscopy..
36. Yuta Nabae, Michal Malon, Stephen Matthew Lyth, Shogo Moriya, Katsuyuki Matsubayashi, Nazrul M. Islam, Shigeki Kuroki, Masa Aki Kakimoto, Jun Ichi Ozaki, Seizo Miyata, The role of Fe in the preparation of carbon alloy cathode catalysts, 9th Proton Exchange Membrane Fuel Cell Symposium (PEMFC 9) - 216th Meeting of the Electrochemical Society, 2009.12, [URL], Pyrolysis of iron phthalocyanine/phenolic resin (FePc/PhRs) and phthtalocyanine/phenolic resin (Pc/PhRs) was studied to clarify the effect of Fe during the preparation of carbon alloy cathode catalysts. FePc/PhRs pyrolyzed at 600 °C showed the best electrocatalytic activity for oxygen reduction. CHN elemental analysis suggests that the catalysts with higher nitrogen content tend to show better catalytic activities. The results of TG/DTA/MS and IR suggest that Fe increases the nitrogen content of the catalysts by enhancing the interaction of phthalocyanine moiety and phenolic resin..
37. Yuta Nabae, Michal Malon, Stephen Matthew Lyth, Shogo Moriya, Katsuyuki Matsubayashi, Nazrul M. Islam, Shigeki Kuroki, Masa Aki Kakimoto, Jun Ichi Ozaki, Seizo Miyata, The role of Fe in the preparation of carbon alloy cathode catalysts, 9th Proton Exchange Membrane Fuel Cell Symposium (PEMFC 9) - 216th Meeting of the Electrochemical Society, 2009.10, Pyrolysis of iron phthalocyanine/phenolic resin (FePc/PhRs) and phthtalocyanine/phenolic resin (Pc/PhRs) was studied to clarify the effect of Fe during the preparation of carbon alloy cathode catalysts. FePc/PhRs pyrolyzed at 600 °C showed the best electrocatalytic activity for oxygen reduction. CHN elemental analysis suggests that the catalysts with higher nitrogen content tend to show better catalytic activities. The results of TG/DTA/MS and IR suggest that Fe increases the nitrogen content of the catalysts by enhancing the interaction of phthalocyanine moiety and phenolic resin..
38. Stephen Matthew Lyth, L. D. Filip, P. C. Cox, S. R P Silva, Novel carbon nanotube based three terminal devices, Technical Digest of the 20th International Vacuum Nanoelectronics Conference, IVNC 07, 2008.07.
39. Stephen Matthew Lyth, S. R P Silva, A study of field emission from glass spheres, coated with carbon nanotubes, 8th IEEE International Vacuum Electronics Conference, IVEC 2007, 2007.12, [URL].
40. Stephen Matthew Lyth, S. R P Silva, Field emission from multiwall carbon nanotubes on flexible paper substrates, 8th IEEE International Vacuum Electronics Conference, IVEC 2007, 2007.12, [URL].
41. Stephen Matthew Lyth, Simon J. Henley, S. R P Silva, Laser ablation of thin carbon nanotube films on glass substrates as transparent field emitters, 8th IEEE International Vacuum Electronics Conference, IVEC 2007, 2007.12, [URL].
42. Stephen Matthew Lyth, R. A. Hatton, S. R P Silva, Li-salt functionalised carbon nanotubes as low work function field emitters, 8th IEEE International Vacuum Electronics Conference, IVEC 2007, 2007.12, [URL].
43. Stephen Matthew Lyth, L. D. Filip, P. C. Cox, S. R P Silva, Novel carbon nanotube based three terminal devices, Technical Digest of the 20th International Vacuum Nanoelectronics Conference, IVNC 07, 2007.12, [URL].
44. Stephen Matthew Lyth, S. R P Silva, A study of field emission from glass spheres, coated with carbon nanotubes, 8th IEEE International Vacuum Electronics Conference, IVEC 2007, 2007.05.
45. Stephen Matthew Lyth, S. R P Silva, Field emission from multiwall carbon nanotubes on flexible paper substrates, 8th IEEE International Vacuum Electronics Conference, IVEC 2007, 2007.05.
46. Stephen Matthew Lyth, Simon J. Henley, S. R P Silva, Laser ablation of thin carbon nanotube films on glass substrates as transparent field emitters, 8th IEEE International Vacuum Electronics Conference, IVEC 2007, 2007.05.
47. Stephen Matthew Lyth, R. A. Hatton, S. R P Silva, Li-salt functionalised carbon nanotubes as low work function field emitters, 8th IEEE International Vacuum Electronics Conference, IVEC 2007, 2007.05.
48. Stephen Matthew Lyth, F. Oyeleye, R. J. Curry, S. R.P. Silva, J. Davis, Field emission from multiwall carbon nanotubes prepared by electrodeposition without the use of a dispersant, Technical Digest of the 18th International Vacuum Nanoelectronics Conference, IVNC 2005, 2005.12, [URL], Carbon nanotubes (CNTs) are ideal candidates to be used as field emission sources. Electrodeposition could provide a viable method to deposit CNTs over large areas as part of an industrialized process. It has been shown l,2,3 that CNTs can be co-deposited with nickel onto various substrates, using a suitable CNT dispersant. In the present study, a multiwall carbon nanotube (MWNT): nickel (Ni) composite has been electrodeposited without the use of a dispersant. The field emission properties of the resulting electrodeposits were studied. Unpurified MWNTs grown by CVD were added to a Ni plating bath comprising of IM NiSO4·6H2O, 0.2M NiCl and 0.5M H3BO3. Due to their hydrophobic nature, MWNTs did not disperse naturally, so the plating solution was placed in a sonic bath for 15 minutes before electrodeposition. Electrochemical measurements were conducted using a μAutolab computer controlled potentiostat with a three-electrode configuration and typical cell volume of 10 cm3. A spiral wound platinum wire served as the counter electrode with a Ag:AgCl wire reference electrode. Cu plates were used as cathodes, with an exposed surface area of 2 cm2. After deposition, samples were thoroughly rinsed in deionised water to remove Ni salts. The resulting electrodeposits were imaged using a scanning electron microscope (FIG.1) Importantly, these deposits were observed after the samples were thoroughly rinsed in deionised water, suggesting that there is a strong adhesion between the nickel coated nanotubes and the substrate surface. FIG.1 (a) shows MWNTs (0.013 mg/ml) electrodeposited directly after sonication. Note that a thick Ni coating is not observed (see inset), and that uniform MWNT deposition is observed over a relatively large area. FIG.1(b) shows MWNTs deposited with the same solution after five minutes. A much thicker Ni coating indicates that a relatively higher concentration of Ni to MWNT was present. This was probably due to a rebundling of MWNTs over time, after the sonication process. FIG.1(c) and (d) show MWNTs deposited with a much lower concentration (0.005 mg/ml), and therefore relatively higher concentration of Ni, resulting in thicker Ni coating. Beads of Ni (visible in FIG.1(d)), approximately one micron in diameter completely encased the MWNTs, previously observed by Aria et al.,4 using a poly(acrylic acid) dispersant. Subsequently, the substrates were subjected to field emission characterisation using a 5 mm spherical stainless steel anode. The emission current was recorded as a function of macroscopic electric field at a vacuum of around 10 -6 mbar. The threshold field was taken to be the field at which an emission current of 1 nA was detected and the macroscopic field was calculated by dividing the applied voltage by the electrode gap, which was typically 25 μm. Threshold fields of the order 20 V/μm were observed (FIG.2), after conditioning. It is expected that by altering the deposition conditions, the much lower threshold fields would be observed..
49. Stephen Matthew Lyth, F. Oyeleye, R. J. Curry, S. R P Silva, J. Davis, Field emission from multiwall carbon nanotubes prepared by electrodeposition without the use of a dispersant, Technical Digest of the 18th International Vacuum Nanoelectronics Conference, IVNC 2005, 2005.07, Carbon nanotubes (CNTs) are ideal candidates to be used as field emission sources. Electrodeposition could provide a viable method to deposit CNTs over large areas as part of an industrialized process. It has been shown l,2,3 that CNTs can be co-deposited with nickel onto various substrates, using a suitable CNT dispersant. In the present study, a multiwall carbon nanotube (MWNT): nickel (Ni) composite has been electrodeposited without the use of a dispersant. The field emission properties of the resulting electrodeposits were studied. Unpurified MWNTs grown by CVD were added to a Ni plating bath comprising of IM NiSO4·6H2O, 0.2M NiCl and 0.5M H3BO3. Due to their hydrophobic nature, MWNTs did not disperse naturally, so the plating solution was placed in a sonic bath for 15 minutes before electrodeposition. Electrochemical measurements were conducted using a μAutolab computer controlled potentiostat with a three-electrode configuration and typical cell volume of 10 cm3. A spiral wound platinum wire served as the counter electrode with a Ag:AgCl wire reference electrode. Cu plates were used as cathodes, with an exposed surface area of 2 cm2. After deposition, samples were thoroughly rinsed in deionised water to remove Ni salts. The resulting electrodeposits were imaged using a scanning electron microscope (FIG.1) Importantly, these deposits were observed after the samples were thoroughly rinsed in deionised water, suggesting that there is a strong adhesion between the nickel coated nanotubes and the substrate surface. FIG.1 (a) shows MWNTs (0.013 mg/ml) electrodeposited directly after sonication. Note that a thick Ni coating is not observed (see inset), and that uniform MWNT deposition is observed over a relatively large area. FIG.1(b) shows MWNTs deposited with the same solution after five minutes. A much thicker Ni coating indicates that a relatively higher concentration of Ni to MWNT was present. This was probably due to a rebundling of MWNTs over time, after the sonication process. FIG.1(c) and (d) show MWNTs deposited with a much lower concentration (0.005 mg/ml), and therefore relatively higher concentration of Ni, resulting in thicker Ni coating. Beads of Ni (visible in FIG.1(d)), approximately one micron in diameter completely encased the MWNTs, previously observed by Aria et al.,4 using a poly(acrylic acid) dispersant. Subsequently, the substrates were subjected to field emission characterisation using a 5 mm spherical stainless steel anode. The emission current was recorded as a function of macroscopic electric field at a vacuum of around 10 -6 mbar. The threshold field was taken to be the field at which an emission current of 1 nA was detected and the macroscopic field was calculated by dividing the applied voltage by the electrode gap, which was typically 25 μm. Threshold fields of the order 20 V/μm were observed (FIG.2), after conditioning. It is expected that by altering the deposition conditions, the much lower threshold fields would be observed..

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