Direct Electron Transfer of Methanol Dehydrogenase with Carbon Nanotubes

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A4 Artikkeli konferenssijulkaisussa
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Modern day portable devices require ever increasing amount of energy. Fuel cells are one answer to demand for longer use times and quick recharge independent of an electric network. The use of hydrogen fuel cells for these kinds of applications has not been widespread, because storage of a required volume of hydrogen gas has been expensive or complicated. One solution to this is producing hydrogen in-situ from more easily storable compounds, e.g. methanol or ethanol. Reformers using inorganic catalyst are either expensive or require temperatures not suitable for light and portable devices. Enzymes are known to oxidize these fuels at room temperature and can be used in in-situ hydrogen production. In this study, the use of methanol dehydrogenase enzyme (MDH) for electrochemical reformation of methanol is investigated. The focus is in improving the electrochemical contact between a carbon electrode and MDH with carbon nanotubes (CNT). Electrodes were prepared with depositions of single-walled CNTs and multi-walled CNTs. These layers could be modified with polymers and cross-linkers to improve their electrochemical performance and stability. Subsequently, the electrodes were dipped in MDH solution at +4°C overnight to allow the absorption of MDH to CNT/polymer layer. The redox behaviour of the electrodes was studied by cyclic voltammetry in phosphate buffer solution (pH 9.5) under nitrogen. The preliminary results show a redox peak pair appearing after enzyme dipping. The calculated formal potential is -140 mV vs SCE. This corresponds quite well with the redox potential of the cofactor of the MDH, pyrroloquinoline quinone (PQQ), at alkaline conditions1. References 1. Hsi-Jung Jao, Pei-Yi Tsai and Chong M. Wang, J. Electroanal. Chem. 2007, 606, 141.
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Kanninen , P , Kallio , T , Ruiz , V & Kontturi , K 2009 , ' Direct Electron Transfer of Methanol Dehydrogenase with Carbon Nanotubes ' .