Decomposition of Carbon Dioxide over the Putative Cubic Spinel Nanophase Cobalt, Nickel, and Zinc Ferrites
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- 作者：Camilla Nordhei ; Karina Mathisen ; Igor Bezverkhyy ; David Nicholson
- 刊名：Journal of Physical Chemistry C
- 出版年：2008
- 出版时间：April 24, 2008
- 年：2008
- 卷：112
- 期：16
- 页码：6531 - 6537
- 全文大小：120K
- 年卷期：v.112,no.16(April 24, 2008)
- ISSN：1932-7455
文摘
Nanophase (4-6 nm) cobalt, nickel, and zinc spinel ferrites were synthesized by coprecipitation, and thedecomposition of carbon dioxide at 300 
C was studied. Oxygen deficiency was obtained by reducing thematerials in hydrogen. The divalent metals strongly influence the extent of the reactions; oxygen-deficientnickel ferrite was found to reduce three and nine times more carbon dioxide than the zinc and cobalt analogues,respectively. Carbon monoxide rather than carbon is produced for all of these ferrites. The reducibility inhydrogen and the degrees of oxygen-deficiencies were studied by X-ray absorption spectroscopy. The X-rayabsorption near edge structure reveals that removing oxygen from the spinels leads to the concomitant reductionof iron(III) to iron(II), while the valence state of the divalent metal is unchanged. Of the three ferrites, nickelferrite exhibits the highest degree of oxygen-deficiency. Extended X-ray absorption fine structure of the nickelferrite shows that, although minor amounts of metallic nickel are expelled through over-reduction, the materialis oxygen-deficient in a putative spinel structure.
C was studied. Oxygen deficiency was obtained by reducing thematerials in hydrogen. The divalent metals strongly influence the extent of the reactions; oxygen-deficientnickel ferrite was found to reduce three and nine times more carbon dioxide than the zinc and cobalt analogues,respectively. Carbon monoxide rather than carbon is produced for all of these ferrites. The reducibility inhydrogen and the degrees of oxygen-deficiencies were studied by X-ray absorption spectroscopy. The X-rayabsorption near edge structure reveals that removing oxygen from the spinels leads to the concomitant reductionof iron(III) to iron(II), while the valence state of the divalent metal is unchanged. Of the three ferrites, nickelferrite exhibits the highest degree of oxygen-deficiency. Extended X-ray absorption fine structure of the nickelferrite shows that, although minor amounts of metallic nickel are expelled through over-reduction, the materialis oxygen-deficient in a putative spinel structure.