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Investigation of Iron Oxide Morphology in a Cyclic Redox Water Splitting Process for Hydrogen Generation
Department of Mechanical and Aerospace Engineering, University of Florida, P.O. Box 116300, Gainesville, FL 32611-6300, USA
* Author to whom correspondence should be addressed.
Received: 25 September 2012; in revised form: 19 October 2012 / Accepted: 19 October 2012 / Published: 23 October 2012
Abstract: A solar fuels generation research program is focused on hydrogen production by means of reactive metal water splitting in a cyclic iron-based redox process. Iron-based oxides are explored as an intermediary reactive material to dissociate water molecules at significantly reduced thermal energies. With a goal of studying the resulting oxide chemistry and morphology, chemical assistance via CO is used to complete the redox cycle. In order to exploit the unique characteristics of highly reactive materials at the solar reactor scale, a monolithic laboratory scale reactor has been designed to explore the redox cycle at temperatures ranging from 675 to 875 K. Using high resolution scanning electron microscope (SEM) and electron dispersive X-ray spectroscopy (EDS), the oxide morphology and the oxide state are quantified, including spatial distributions. These images show the change of the oxide layers directly after oxidation and after reduction. The findings show a significant non-stoichiometric O/Fe gradient in the atomic ratio following oxidation, which is consistent with a previous kinetics model, and a relatively constant, non-stoichiometric O/Fe atomic ratio following reduction.
Keywords: solar fuels; SEM; EDS; steam-iron process; water splitting; magnetite
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Bobek, M.M.; Stehle, R.C.; Hahn, D.W. Investigation of Iron Oxide Morphology in a Cyclic Redox Water Splitting Process for Hydrogen Generation. Materials 2012, 5, 2003-2014.
Bobek MM, Stehle RC, Hahn DW. Investigation of Iron Oxide Morphology in a Cyclic Redox Water Splitting Process for Hydrogen Generation. Materials. 2012; 5(10):2003-2014.
Bobek, Michael M.; Stehle, Richard C.; Hahn, David W. 2012. "Investigation of Iron Oxide Morphology in a Cyclic Redox Water Splitting Process for Hydrogen Generation." Materials 5, no. 10: 2003-2014.