The surface chemistry of iron oxide nanocrystals: surface reduction of γ-Fe2O3 to Fe3O4 by redox-active catechol surface ligands

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DOI

  • P. Daniel, Johannes Gutenberg Univ Mainz, Johannes Gutenberg University of Mainz, Inst Anorgan Chem & Analyt Chem
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  • S. I. Shylin, Johannes Gutenberg Univ Mainz, Johannes Gutenberg University of Mainz, Inst Anorgan Chem & Analyt Chem
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  • H. Lu, Max Planck Inst Polymer Res, Max Planck Society
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  • M. N. Tahir, Johannes Gutenberg Univ Mainz, Johannes Gutenberg University of Mainz, Inst Anorgan Chem & Analyt Chem
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  • M. Panthoefer, Johannes Gutenberg Univ Mainz, Johannes Gutenberg University of Mainz, Inst Anorgan Chem & Analyt Chem
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  • T. Weidner
  • A. Moeller
  • V. Ksenofontova, Johannes Gutenberg Univ Mainz, Johannes Gutenberg University of Mainz, Inst Anorgan Chem & Analyt Chem
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  • W. Tremel, Johannes Gutenberg Univ Mainz, Johannes Gutenberg University of Mainz, Inst Anorgan Chem & Analyt Chem

The effect of surface functionalization on the structural and magnetic properties of catechol-functionalized iron oxide magnetic (gamma-Fe2O3) nanocrystals was investigated. gamma-Fe2O3 nanocrystals (NCs) were synthesized from iron acetyl acetonate in phenyl ether with 1,2-tetradecanediol, oleic acid, and oleylamine. X-ray powder diffraction in combination with Mossbauer spectroscopy revealed the presence of gamma-Fe2O3 (maghemite) particles only. Replacement of oleic acid (OA) with catechol-type 3,4-dihydroxyhydrocinnamic acid (DHCA) or polydentate polydopamine acrylate (PDAm) surface ligands leads to a pronounced change of the magnetic behavior of the gamma-Fe2O3 nanocrystals and separated them into two distinctive magnetic entities. XPS and Mossbauer spectroscopy revealed the shell to be reduced with a magnetite (Fe2O3) contribution of up to 33% of the total mass while the core remained maghemite (gamma-Fe2O3). The magnetic interaction between the maghemite core and the magnetite shell strongly reduced the anisotropy constant of the nanocrystals and the effective magnetization. Our experiments show that the surface chemistry strongly affects the phase distribution and the macroscopic magnetic properties of iron oxide nanopowders.

Original languageEnglish
JournalJournal of Materials Chemistry C
Volume6
Issue2
Pages (from-to)326-333
Number of pages8
ISSN2050-7526
DOIs
Publication statusPublished - 2018
Externally publishedYes

    Research areas

  • MAGNETIC NANOPARTICLES, FUNCTIONAL MOLECULES, COMPLEXES, MAGHEMITE, DOPAMINE, SHELL, CRYSTALLINE, COMPOSITES, STABILITY, MOSSBAUER

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