Silica coating of CeO2 nanoparticles by a fast microwave irradiation method

Abstract 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 CeO 2 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 CeO 2 nanoparticles surface through Ce–O–Si chemical bonds. The coating extent was increased with increasing in TEOS loading and surface characteristics of coated CeO 2 nanoparticles with high silica extents showed similar electrokinetic behavior to SiO 2 particles. The high resolution transmission electron microscope (HR-TEM) images also showed that SiO 2 coated the cubic shaped CeO 2 nanoparticles as thin uniform layers (5 nm). The catalytic activities of non-coated and silica coated CeO 2 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 CeO 2 nanoparticles were evaluated by UV–vis spectroscopic analyses. These analytical results indicated that silica coated CeO 2 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 CeO 2 nanoparticles.