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α-Fe2O3 Nanowire Array Based Electrodes for Self-Driven Photoelectrochemical Cells

Boris D. Chernomordik, Chemical Engineering, University of Louisville, 106 Ernst Hall, Department of Chemical Engineering,, University of Louisville, Louisville, KY 40292, Uros Cvelbar, Plasma Laboratory F4, Jozef Stefan Institute, Jamova 39, Ljubljana, SI-1000, Slovenia, Vidhya Chakrapani, Chemical Engineering, University of Lousiville, Room 311, Ernst Hall, Univeristy of Louisville, Louisville, KY 40292, Miran Mozetic, Department for Surface Engineering, Jozef Stefan Institute, Jamova 39, Ljubljana, Slovenia, and Mahendra K. Sunkara, Department of Chemical Engineering, University of Louisville, 106 Ernst Hall, Department of Chemical Engineering,, University of Louisville, Louisville, KY 40292.

Iron oxide, Fe2O3, is a promising material for water splitting reaction using solar energy.[1-2] Even the recent efforts, however, using Fe2O3 thin film materials reported low efficiencies due to poor carrier transport within these films.[3-4] In this regard, we have been working on a-Fe2O3 nanowire arrays as possible thin film materials systems for improved carrier mobility during photoelectrochemical water splitting reaction.

Recently, we developed a novel method to synthesize arrays of α-Fe2O3 nanowires, which are single crystal and have highly ordered oxygen vacancy plane.[5-6] The nanowire arrays are directly synthesized on metallic substrates using low-temperature RF plasma oxidation without the use of any foreign metal catalysts. The nanowire growth is spontaneous and the process lasts only seconds. This method could be scaled up for manufacturing of large area nanowire arrays on metallic foils. As one-dimensional nanostructures, these nanowires offer many other benefits to PEC electrolysis, such as high surface area, reduced charge carrier diffusion distance, and a preferential direction for charge diffusion. In this presentation, we will provide both synthesis and their photoelectrochemical properties of a-Fe2O3 nanowire arrays grown on Fe foils.

References

1. K.L. Hardee, A.J. Bard, Semiconducting electrodes. 5. Application of Chemically Vapor Deposited Iron Oxide Films to Photosensitized Electrolysis", J. of the Electrochemical Society 1976, 123, (7), 1024-1026.

2. J.H. Kennedy, M. Anderman, Photoelectrolysis of Water at alpha- Fe2O3 electrodes in Acidic Solution", J. of the Electrochemical Society 1983, 130, (4),

3. T. Lindgren, H.L. Wang, N. Beermann, L. Vayssieres, A. Hagfeldt, S.E. Lindquist, Aqueous photoelectrochemistry of hematite nanorod array, "Solar Energy Materials and Solar Cells", 2002, 71, (2), 231-243.

4. W.B. Ingler, S.U.M. Khan, "A self-driven p/n-Fe2O3 tandem photoelectrochemical cell for water splitting", Electrochemical and Solid State Letters 2006, 9, (4), G144-G146.

5. U. Cvelbar, Z. Chen, M.K. Sunkara and M. Mozetic, "Spontaneous growth of superstructure α-Fe2O3 nanowire and nanobelt arrays in reactive oxygen plasma", Revision Submitted, Small (2008).

6. Z. Chen, U. Cvelbar, M. Mozetic, J. He and M.K. Sunkara, "Long-Range Ordering of Oxygen-Vacancy Planes in r-Fe2O3 Nanowires and Nanobelts", Chemistry of Materials, 20 (9), 3224 - 3228 (2008).


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