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2019
Journal Article
Titel
Chemistry of Shape-Controlled Iron Oxide Nanocrystal Formation
Abstract
Herein, we demonstrate that meticulous and in-depth analysis of the reaction mechanisms of nanoparticle formation is rewarded by full control of the size, shape, and crystal structure of superparamagnetic iron oxide nanocrystals during synthesis. Starting from two iron sources, iron(II) and iron(III) carbonate, a strict separation of oleate formation from the generation of reactive pyrolysis products and concomitant nucleation of iron oxide nanoparticles was achieved. This protocol enabled us to analyze each step of nanoparticle formation independently in depth. The progress of the entire reaction was monitored via matrix-assisted laser desorption ionization time-of-flight mass spectrometry and gas chromatography, thus providing insight into the formation of various iron oleate species prior to nucleation. Interestingly, due to the intrinsic strongly reductive pyrolysis conditions of the oleate intermediates and redox process in early stages of the synthesis, pristine iron oxide nuclei were composed exclusively from wüstite irrespective of the oxidation state of the iron source. Controlling the reaction conditions provided a very broad range of size- and shape-defined monodispersed iron oxide nanoparticles. Curiously, after nucleation, star-shaped nanocrystals were obtained that underwent metamorphism toward cubic-shaped particles. Electron energy loss spectroscopy tomography revealed ex post oxidation of the primary wustite nanocrystal, providing a full 3D image of Fe2+ and Fe3+ distribution within. Overall, we developed a highly flexible synthesis, yielding multi-gram amounts of well-defined iron oxide nanocrystals of different sizes and morphologies.
Author(s)
Feld, Artur
Institute of Physical Chemistry, Hamburg University, Grindelallee 117, D-20146 Hamburg, Germany The Hamburg Center for Ultrafast Imaging, Hamburg University, Luruper Chaussee 149, D-22761 Hamburg, Germany
Weimer, Agnes
Institute of Physical Chemistry, Hamburg University, Grindelallee 117, D-20146 Hamburg, Germany The Hamburg Center for Ultrafast Imaging, Hamburg University, Luruper Chaussee 149, D-22761 Hamburg, Germany
Kornowski, Andreas
Institute of Physical Chemistry, Hamburg University, Grindelallee 117, D-20146 Hamburg, Germany The Hamburg Center for Ultrafast Imaging, Hamburg University, Luruper Chaussee 149, D-22761 Hamburg, Germany
Winckelmans, Naomi
Electron Microscopy for Materials Science (EMAT), Department Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
Merkl, Jan-Philip
Institute of Physical Chemistry, Hamburg University, Grindelallee 117, D-20146 Hamburg, Germany The Hamburg Center for Ultrafast Imaging, Hamburg University, Luruper Chaussee 149, D-22761 Hamburg, Germany
Kloust, Hauke
Institute of Physical Chemistry, Hamburg University, Grindelallee 117, D-20146 Hamburg, Germany The Hamburg Center for Ultrafast Imaging, Hamburg University, Luruper Chaussee 149, D-22761 Hamburg, Germany
Zierold, Robert
Center for Hybrid Nanostructures, Hamburg University, Luruper Chaussee 149, 22761 Hamburg, Germany
Schmidtke, Christian
Institute of Physical Chemistry, Hamburg University, Grindelallee 117, D-20146 Hamburg, Germany
Riedner, Maria
Department of Chemistry, Hamburg University, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
Bals, Sara
Electron Microscopy for Materials Science (EMAT), Department Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
Weller, Horst
Institute of Physical Chemistry, Hamburg University, Grindelallee 117, D-20146 Hamburg, Germany The Hamburg Center for Ultrafast Imaging, Hamburg University, Luruper Chaussee 149, D-22761 Hamburg, Germany Fraunhofer-CAN, Grindelallee 117, D-20146 Hamburg, Germany Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O BOX 80203 Jeddah 21589, Saudi Arabia
Project(s)
M3 Maßgeschneiderte multiskalige Materialsysteme