Template-free controlled hydrothermal synthesis for monodisperse flowerlike porous CeO2 microspheres and their superior catalytic reduction of NO with NH3

Monodisperse flowerlike porous CeO2 microspheres with the diameters of 2-5 mu m composed of numerous nanosheets as the petals with variable thickness of 40-200 nm have been successfully synthesized via a facile hydrothermal technique. Various techniques have been applied to investigate the CeO2 nanostructures, including XRD, SEM, TEM, XPS, Raman spectra, PL spectra, BET, and in situ DRIFT'S. The reaction temperature, reaction time, reaction solution, the amount of H2O2 and ethylenediamine were systematically investigated. It is found that the reaction temperature, reaction time, reaction solution, the amount of H2O2 and ethylenediamine.are key parameters for controlling the final morphology. The flowerlike CeO2 microspheres have a cubic fluorite structure and there are Ce3+ ions and oxygen vacancies in surface of samples. The as-synthesized,CeO2 samples showed enhanced optical properties with the decrease of reaction temperature. Furthermore, flowerlike CeO2 microspheres obtained at 120 degrees C for 48 h displayed a high surface area of 83.81 m(2) g(-1) and narrow pore size of 3.86 nm by N-2 adsorption and desorption measurement. The outstanding catalytic performance for the flowerlike CeO2 microspheres can be attributed to the much larger surface areas, fancy morphology and the best redox behaviour of surface oxygen on the CeO2 surface. (C) 2016 Elsevier B.V. All rights reserved.