Surface characterization and properties of ordered arrays of CeO2 nanoparticles embedded in thin layers of SiO2
Résumé
We demonstrated the surface composite character down to the nanometer scale of SiO2-CeO2 composite high surface area materials, prepared using 5 nm colloidal CeO2 nanoparticle building blocks. These materials are made of a homogeneous distribution of CeO2 nanoparticles in thin layers of SiO2, arranged in a hexagonal symmetry as shown by small-angle X-ray scattering and transmission electron microscopy. Since the preparation route of these composite materials was selected in order to produce SiO2 wall thickness in the range of the CeO2 nanoparticle diameter, these materials display surface nanorugosity as shown by inverse chromatography. Accessibility through the porous volume to the functional CeO2 nanoparticle surfaces was evidenced through an organic acid chemisorption technique allowing quantitative determination of CeO2 surface ratio. This surface composite nanostructure down to the nanometer scale does not affect the fundamental properties of the functional CeO2 nanodomains, such as their oxygen storage capacity, but modifies the acid-base properties of the CeO2 surface nanodomains as evidenced by Fourier transform IR technique. These arrays of accessible CeO2 nanoparticles displaying high surface area and high thermal stability, along with the possibility of tuning their acid base properties, will exhibit potentialities for catalysis, sensors, etc.
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