10:50 - 11:10 Advances in Organic and Inorganic Chemistry

Investigation of the electron transfer of methylene blue onto monolayer graphene electrodes

Michel Wehrhold1,2, Rodrigo M. Iost1,2, Tilmann J. Neubert1,2,3,4 and Kannan Balasubramanian1,2,4,5

1Micro- and Nano Analytical Sciences, SALSA - School of Analytical Sciences Adlershof, Albert-Einstein-Straße 5-9, 12489, Berlin, GER

2Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, GER

3Institut für Silizium-Photovoltaik, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Kekuléstr. 5, 12489, Berlin, GER

4IRIS Adlershof, Humboldt-Universität zu Berlin, Zum Großen Windkanal 6, 12489, Berlin, GER

5Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, GER

Graphene is single atomic layer of sp2-bonded carbon. Because of its 2D structure, remarkable properties are expected, such as an anomalous high electron mobility 1. Graphene is considered to be a material with outstanding properties and hence a high potential for numerous applications 2. In this work, electron transfer (ET) has been studied using monolayer graphene as electrode material. While the ET between monolayer graphene and inorganic redox-active molecules were studied before 3, there is only little information about the ET properties using small organic molecules. For the first time, the electrochemical properties of monolayer graphene using Methylene Blue (MB) as redox-active molecule were investigated systematically. MB is widely used as a redox indicator, e.g. for chemical and biological sensors 4 5 6. Mostly, MB was adsorbed in composites on the electrode surface in high concentration. Since it is already known that MB aggregates in higher concentration, we used micro molar MB concentrations, to ensure that only MB monomer was present. The ET properties of graphene were studied using cyclic voltammetry (CV) experiments. Using different analyses methods 7, we were able to gain fundamental information about the apparent diffusion coefficient D, the heterogeneous rate constant for the ET kHET and the extent of the reversibility of the redox process. Additionally, we patterned graphene using photolithography, to investigate the effect of the electrode size on the thermodynamic and kinetic aspects of the ET. We were able to see an impact of the electrode size and the contact area on the thermodynamic properties of the ET.

  1. K. S. Novoselov, et al, Science, (2004), 306, 666

  2. A. K. Geim, et al, Nat Mater, (2007), 6, 183-191

  3. M. Velicky, et al, ACS Nano, (2014), 8, 10089-10100

  4. J. Ye and R. P. Baldwin, Anal Chem, (1988), 60, 2263-2268

  5. A. Erdem, et al, Analytica Chimica Acta, (2000), 422, 139-149

  6. J.-Z. Xu, et al, Electroanal, (2003), 15, 219-224

  7. R. G. Compton and C. E. Banks, Understanding Voltammetry, 2nd edition, (2011)