期刊
SMALL
卷 18, 期 20, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/smll.202200414
关键词
iron oxide nanoparticles; iron stearate; nucleation mechanisms; thermal decomposition; vesicle-like nanoreactors
类别
资金
- Region Alsace, France
- Labex Chimie des Systemes Complexes, University of Strasbourg, France
- Labex CSC
- Alsace contre le cancer
- INCA [PRTK14, THERAMAG 2014-225]
- French national agency for research (ANR) [ANR-16-CE05-0011]
- EQUIPEX program of the Agence Nationale de Recherche (France) [ANR-11-EQPX-0041]
- Agence Nationale de la Recherche (ANR) [ANR-11-EQPX-0041] Funding Source: Agence Nationale de la Recherche (ANR)
Thermal decomposition is an efficient method for synthesizing nanosized metal oxides with controlled structures and properties. In the synthesis of iron oxide nanoparticles, the nucleation mechanism has been found to occur within vesicle-like nanoreactors, providing a new understanding of the synthesis process. This discovery paves the way for better control over the synthesis and properties of metal oxide nanoparticles.
Thermal decomposition is a very efficient synthesis strategy to obtain nanosized metal oxides with controlled structures and properties. For the iron oxide nanoparticle synthesis, it allows an easy tuning of the nanoparticle's size, shape, and composition, which is often explained by the LaMer theory involving a clear separation between nucleation and growth steps. Here, the events before the nucleation of iron oxide nanocrystals are investigated by combining different complementary in situ characterization techniques. These characterizations are carried out not only on powdered iron stearate precursors but also on a preheated liquid reaction mixture. They reveal a new nucleation mechanism for the thermal decomposition method: instead of a homogeneous nucleation, the nucleation occurs within vesicle-like-nanoreactors confining the reactants. The different steps are: 1) the melting and coalescence of iron stearate particles, leading to droplet-shaped nanostructures acting as nanoreactors; 2) the formation of a hitherto unobserved iron stearate crystalline phase within the nucleation temperature range, simultaneously with stearate chains loss and Fe(III) to Fe(II) reduction; 3) the formation of iron oxide nuclei inside the nanoreactors, which are then ejected from them. This mechanism paves the way toward a better mastering of the metal oxide nanoparticles synthesis and the control of their properties.
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