Investigation of iron oxide morphology in a cyclic redox: Water splitting process for hydrogen generation

Michael M. Bobek, Richard C. Stehle, David W. Hahn

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)2003-2014
Number of pages12
JournalMaterials
Volume5
Issue number10
DOIs
StatePublished - 2012
Externally publishedYes

Keywords

  • EDS
  • Magnetite
  • SEM
  • Solar fuels
  • Steam-iron process
  • Water splitting

ASJC Scopus subject areas

  • Materials Science(all)

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