Effect of rare-earth doping in CeO2 matrix: Correlations with structure, catalytic and visible light photocatalytic properties

Abstract

The nanoparticles involving LaxCe1−x O2–δ system (x = 0.1, 0.2 and 0.5) with various rare earth La3+-doping levels were successfully synthesized and characterized for their structural, catalytic and photocatalytic properties. The structural characterizations (via X-ray diffraction, high-resolution transmission electron microscopy, Raman spectroscopy) confirmed the presence of phase-pure catalyst nanoparticles with desired target stoichiometry; induced lattice strains were correlated with various doping amounts. Raman spectroscopy results illustrated the effect of progressively higher La-doping with increasing peak asymmetry, broadening and shifting of the key peaks to lower energies. The 10% La-doped ceria catalysts depicted superior catalytic reduction and visible light photocatalytic (for the degradation of methylene blue) properties along with promising oxygen storage capacity values. Our results suggest that low (≤ 20%) doping of the rare-earth metal is sufficient for maintaining a balance between catalytic properties and overall deformation (strain, vacancy etc) in the fluorite CeO2 lattice.