Stephen joined Kyushu University as Assistant Professor at I2CNER in 2011. He works on the synthesis and application of a novel form of graphene to a variety of carbon-neutral areas such as fuel cell cathodes / catalysts, proton conducting membranes, hydrogen storage, and CO2 conversion.
Graphene is a single, free-standing sheet of carbon atoms which can be produced, for example, by exfoliating graphite into its constituent layers. It has extremely large surface area, electronic conductivity better than copper, the highest measured thermal conductivity, and the highest strength of any material ever tested. As a relatively new material there is still a great deal of scope for characterizing, understanding, and applying it.
Stephen synthesizes a three-dimensional macroporous graphene-like foam. This can be produced in bulk and routinely doped with heteroatoms, have its surface chemistry modified, or be decorated with nanoparticles. The material can then be tailored to suit various different applications. Of particular interest is nitrogen-doped graphene.
Left: Atomic structure of nitrogen-doped graphene. Grey balls are carbon, and blue balls are nitrogen atoms. Right: Transmission electron microscopy of nitrogen-doped graphene foam, with 200 nm pore-size.
Modified graphene for electrochemical oxygen reduction
Reducing the amount of platinum catalyst is crucial for the long-term utilization of PEM fuel cells. By doping graphene with heteroatoms such as nitrogen, boron, and sulfur, it can become active for electrochemical oxygen reduction in its own right, in both acid and especially alkaline fuel cells. Additionally, when nitrogen-doped graphene is used as a platinum catalyst support, the binding strength between the carbon and the platinum nanoparticles can be improved, helping to increase fuel cell durability, and reduce platinum loading at both the anode and cathode. In this project, these ideas are being fully explored from the synthesis and catalyst level, up to system-level issues. eJournal of Surface Science and Nanotechnology, 10, 29-32 (2012)
Graphene oxide-based proton conducting membranes
Stephen M. Lyth, Masamichi Nishihara
A key technology in PEM fuel cells is the proton-conducting membrane. Currently Nafion is used, which is expensive, and limits cell operation to temperatures below 90ºC. If the temperature can be increased, the cost and efficiency of fuel cells could be improved. Graphene oxide is electronically insulating, and stable at high temperature. The oxygen functional groups provide opportunity for further functionalization of the surface to include proton hopping sites. In this project we are optimizing a proton-conducting graphene oxide membrane and plan to apply these new membranes to high temperature PEM fuel cells, and micro fuel cells.
An important aspect of fuel cell utilization and the hydrogen economy is hydrogen storage. Hydrogen storage materials need to be lightweight, have large surface area, good thermal conductivity, and high hydrogen adsorption capacity. Graphene ticks all of these boxes. In this interdisciplinary project, we will tailor the surface of our graphene foam to maximize the interaction between hydrogen and the surface. Theoretical studies show hydrogen storage capacities greater than DOE targets, and as such this project shows great potential.
Electrochemical conversion of CO2 on graphene
Stephen M. Lyth, Molly Jhong, Paul Kenis
One way to reduce the amount of greenhouse gases that we release into the atmosphere is to capture CO2, and convert it into another less dangerous, more useful molecule. He we have initiated a project using graphene as a catalyst, or catalyst support, to electrochemically convert carbon dioxide into e.g., methanol, formic acid, or syngas (CO). This is a collaborative project with our satellite institute at the University of Illinois. Image credit, Molly Jhong.
The graphene research labs are located in the Demonstration Facility for Future Energies, otherwise known as "Eco House". This is a state-of-the-art new building featuring external green-walls, LED lighting, and solar generated power. We have established a well-stocked chemistry lab within, including fume-hoods, prep benches, glove boxes, high pressure reactors, furnaces, AFM / SPM, and electrochemical characterization equipment. There is also a lab-scale demonstration of integrated hydrogen generation, compression, storage, and utilization.
We are always looking to recruit new undergraduate students, doctoral candidates, technicians, and postdoctoral researchers. If you are interested in working in this exciting field, please contact us directly by email.
Solvothermal Synthesis of Nitrogen-Containing Graphene for Electrochemical Oxygen Reduction, S. M. Lyth, Y. Nabae, N. M. Islam, T. Hayakawa, S. Kuroki, M. Kakimoto, S. Miyata, eJournal of Surface Science and Nanotechnology, 10, 29-32, 2012
Oxygen reduction activity of carbon nitride supported on multiwall carbon nanotubes, S. M. Lyth, Y. Nabae, N. M. Islam, S. Kuroki, M. Kakimoto, S. Miyata, Journal of Nanoscience and Nanotechnology, 12, 1-5, 2012
Electrochemical oxygen reduction of carbon nitride supported on carbon black, S. M. Lyth, Y. Nabae, N. M. Islam, S. Kuroki, M. Kakimoto, S. Miyata, Journal of the Electrochemical Society, 158, B194 (2011)
Electrochemical oxygen reduction on carbon nitride, S. M. Lyth, Y. Nabae, N. M. Islam, S. Kuroki, M. Kakimoto, J. Ozaki, S. Miyata, Electrochemical Society Transactions, 28, 11 (2010)
The role of Fe species in the pyrolysis of Fe phthalocyanine and phenolic resin for preparation of carbon-based cathode catalysts, Y. Nabae, S. Moriya, K. Matsubayashi, S. M. Lyth, M. Malon, L. Wu, N. M. Islam, S. Kuroki, M. Kakimoto, S. Miyata, J. Ozaki, Carbon, 48, 2613 (2010)
The role of Fe in the preparation of carbon alloy cathode catalysts, Y. Nabae, M. Malon, S. M. Lyth, S. Moriya, K. Matsubayashi, N. Islam, S. Kuroki, M. Kakimoto, J. Ozaki, S. Miyata, Electrochemical Society Transactions, 25, 463 (2009)
Carbon nitride as a non-precious catalyst for electrochemical oxygen reduction, S. M. Lyth, Y. Nabae, S. Moriya, S. Kuroki, M. Kakimoto, J. Ozaki and S. Miyata, Journal of Physical Chemistry C, 113, 20148 (2009)
Resonant behaviour observed in electron field emission from acid functionalized multiwall carbon nanotubes , S. M. Lyth and S. R. P. Silva, Applied Physics Letters, 94, 123102 (2009)
Secondary nanotube growth on aligned carbon nanofiber arrays for superior field emission, P. C. P. Watts, S. M. Lyth, S. J. Henley and S. R. P. Silva, Journal of Nanoscience and Nanotechnology, 8, 2147 (2008)
Field emission from multiwall carbon nanotubes on paper substrates, S. M. Lyth and S. R. P. Silva, Applied Physics Letters,90, 173124 (2007)
Efficient field emission from Li-salt functionalized multiwall carbon nanotubes on flexible substrates, S. M. Lyth, R. A. Hatton and S. R. P. Silva, Applied Physics Letters,90, 013120 (2007)
Polymer supported carbon nanotube arrays for field emission and sensor devices, P. C. P. Watts, S. M. Lyth, E. Mendoza and S. R. P. Silva, Applied Physics Letters, 89, 103113 (2006)
Field emission from multiwall carbon nanotubes prepared by electrodeposition without the use of a dispersant , S. M. Lyth, F. Oyeleye, R. J. Curry, J. Davis and S. R. P. Silva, Journal of Vacuum Science and Technology B, 24, 1362 (2006)