Facile preparation of CeO2 microspheres with high surface area by ultrasonic spray pyrolysis

Abstract

Abstract CeCl3 solution was used as a precursor to prepare CeO2 microspheres by ultrasonic spray pyrolysis (USP). This is a green process that allows the transformation from CeCl3 to CeO2 without consuming any precipitant. The prepared material was investigated through various analysis technologies, such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), energy dispersive X-ray spectroscopy (EDS), N2 adsorption-desorption and X-ray photoelectron spectroscopy (XPS). The prepared sample was confirmed as high purity CeO2 microspheres, and two different microstructures were observed. The microsphere surface area was 86.5 m2/g according to the Brunauer-Emmett-Teller method. The microsphere diameter ranged from 0.09 μm to 3.86 μm and the microsphere surface was covered by numerous nanoparticles. The observed nanoparticles ranged in size from 19 nm to 200 nm as determined from FESEM and HRTEM images. The concentrations of Ce4+, Ce3+, residual chloride and oxygen vacancy in CeO2 were studied by relative sensitivity factors based on the XPS results. Finally, the data suggested the possible formation mechanism of the CeO2 microsphere structure.