Silica coating of CeO2 nanoparticles by a fast microwave irradiation method

A rapid and simple route for silica coating with base catalyzed hydrolysis and condensation of tetraethoxysilane (TEOS) precursor in water–ethanol solvent using microwave irradiation to encapsulate CeO2 nanoparticles with a silica shell is studied. From X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectra analysis, it was confirmed that silica in the coating is attached on the CeO2 nanoparticles surface through Ce–O–Si chemical bonds. The coating extent was increased with increasing in TEOS loading and surface characteristics of coated CeO2 nanoparticles with high silica extents showed similar electrokinetic behavior to SiO2 particles. The high resolution transmission electron microscope (HR-TEM) images also showed that SiO2 coated the cubic shaped CeO2 nanoparticles as thin uniform layers (5 nm). The catalytic activities of non-coated and silica coated CeO2 nanoparticles for oxidation of organic compound were evaluated by degradation of methylene blue in air atmosphere at 403 K. Furthermore, the optical properties of non-coated and silica coated CeO2 nanoparticles were evaluated by UV–vis spectroscopic analyses. These analytical results indicated that silica coated CeO2 nanoparticles with thin silica layer could be prepared using sol–gel method assisted by microwave irradiation within 2 min and this material showed better performances than original CeO2 nanoparticles.