Electronic structure of MxOy/SiO2 (M=Mg, Cu) inorganic nanocomposites

Abstract

The electronic structure of MxOy/SiO2 (M = Mg, Cu) inorganic nanocomposites was investigated using ultrasoft X-ray emission (USXES) and X-ray photoelectron spectroscopy (XPS) methods. The XPS core-level binding energies (BEs) for MxOy/SiO2 were determined. The USXES SiLα- and OKα-spectra for the compounds were derived. It was found that the energy distribution of the valence Sisd- and Oр-electrons did not change with the increase of CuxOy content in CuxOy/SiO2 nanocomposite. Whereas, contribution of Sid-electrons decreased and contribution of Sis-electrons increased in SiO2 valence band when content of MgxOy increased from 0.2 to 1 mmol. It was revealed that oxygen ions in MgxOy + SiO2 sample with a content of MgxOy 3 mmol were in different charge states. However, in MgxOy + SiO2 samples with MgxOy content 0.2 and 1 mmol oxygen ions were in the same charge states. In CuxOy + SiO2 samples with CuxOy content 0.2, 1, and 3 mmol charge states of oxygen ions were identical. Treatment of SiO2 particles with the aMxOy oxides does not influence significantly the charge states of Si atoms and they are in the formal valence similar to that in SiO2. In aCuxOy/SiO2 (a = 0.2, 1, 3 mmol) the XPS Si 2p, Si 2s, and O 1s core-level BEs remain constant. In aMgxOy/SiO2 (a = 0.2, 1, 3 mmol) the XPS Si 2p, Si 2s, and O 1s core-level BEs are similar.