Analysis of Co3O4-SnO2 and Co3O4-Fe2O3 nanosystems by x-ray photoelectron spectroscopy

In this work, x-ray photoelectron spectroscopy was employed to characterize the surface composition and elemental chemical states of supported Co3O4-SnO2 and Co3O4-Fe2O3 nanocomposites. The present materials were prepared on Si(100) substrates by the chemical vapor deposition of cobalt oxide under O2 + H2O atmospheres, followed by the tailored introduction of SnO2 or Fe2O3 by means of radio frequency-sputtering. Material structural and morphological characterization revealed the formation of nanocomposite heterostructures involving a conformal Co3O4 coverage by SnO2 or Fe2O3 overlayers. Survey spectra as well as detailed scans of C 1s, O 1s, Co 2p, Sn 3d, and Fe 2p regions are presented and critically discussed. The results provide evidence for the formation of pure and oxygen-deficient nanocomposites, and the occurrence of an electronic interplay between the single oxide constituents.