Ceria Nanocubes: Dependence of the Electronic Structure on Synthetic and Experimental Conditions

Abstract

The properties of nanostructured ceria are both size- and shape-dependent. Here, ∼3–10 nm ceria nanocubes having exposed (002) surfaces were hydrothermally synthesized. For the first time, the electronic properties of such nanocubes were systematically studied using X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. Comparisons of the collected Ce 3d XPS spectra after a single sweep revealed that the concentration of Ce3+ present within the nanocubes is independent of the particle size and the Ce precursor used. Ce 3d spectra collected after averaging 20 sweeps demonstrated the reduction of Ce4+, and that the degree of reduction was also independent of the synthetic conditions. This observed surface reduction/damage is mainly the result of exposure to high intensity X-ray radiation. These conclusions were further confirmed through examination of Ce M4,5- and N4,5-edge XANES spectra. On the basis of these results, it is clear that the concentration of Ce3+ on the surface of ceria nanocubes...