Nanostructuration de ferrites de cobalt CoxFe3-xO4 : Effets sur la catalyse et la détection de gaz polluants

Abstract : Different synthesis methods such as hydrothermal, solvothermal and thermal decomposition were developed to control nanoparticles shape and composition. The influence of synthesis parameters such as the nature of surfactants, the solvents, temperature and time of synthesis were also investigated. The powders were characterized by X-ray Diffraction and Transmission Electron Microscopy coupled with Dispersive Energy Spectroscopy. The catalytic and detection properties were evaluated in presence of CO and NO2 in synthetic air. CoxFe3-xO4 (x = 1, 1.5 ) nanooctahedra with 15-20 nm were produced by hydrothermal synthesis using different surfactants (CTAB, SDS and PVP). Nanocubes of CoFe2O4 were successfully obtained by solvothermal synthesis using oleylamine as surfactant. Nanooctahedra of CoxFe3-xO4 with x = 1.5 have higher activity for the CO conversion than those with x=1, and the conversion starts at lower temperature for the nanocubes. The nanocubes show lower sensitivity for the detection of NO2 than the nanooctahedra which indicates that the {111} faces are more reactive than the {100} ones in cobalt ferrites nanoparticles.
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Indira Aritana Fernandes de Medeiros. Nanostructuration de ferrites de cobalt CoxFe3-xO4 : Effets sur la catalyse et la détection de gaz polluants. Matériaux. Université de Toulon; Universidade federal do Rio Grande do Norte (Natal, Brésil), 2018. Français. ⟨NNT : 2018TOUL0007⟩. ⟨tel-02275813⟩

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