Growth and characterization of ceria thin films and Ce-dopedγ-Al2O3 nanowires using sol–gel techniques

Abstract

γ-Al2O3 is a well known catalyst support. The addition of Ce toγ-Al2O3 is known to beneficially retard the phase transformation ofγ-Al2O3 toα-Al2O3 and stabilize theγ-pore structure. Inthis work, Ce-doped γ-Al2O3 nanowires have been prepared by a novel method employing an anodic aluminium oxide(AAO) template in a 0.01 M cerium nitrate solution, assisted by urea hydrolysis. Calcination at500 °C for 6 h resulted in the crystallization of the Ce-doped AlOOH gel to form Ce-dopedγ-Al2O3 nanowires.Ce3 + ions within the nanowires were present at a concentration of < 1 at.%. On the template surface, a nanocrystallineCeO2 thin film was deposited with a cubic fluorite structure and a crystallite size of 6–7 nm.Characterization of the nanowires and thin films was performed using scanning electronmicroscopy, transmission electron microscopy, electron energy loss spectroscopy, x-rayphotoelectron spectroscopy and x-ray diffraction. The nanowire formation mechanism and ureahydrolysis kinetics are discussed in terms of the pH evolution during the reaction. The Ce-dopedγ-Al2O3 nanowires are likely to find useful applications in catalysis and this novel method can beexploited further for doping alumina nanowires with other rare earth elements.