ZnO/MgO Nanocomposites by Wet Impregnation: An XPS study

Zinc oxide/magnesium oxide nanocomposite powders were prepared by wet impregnation of nanosized magnesia powders. The supporting magnesia was obtained by precipitation from a solution of magnesium nitrate. The samples are characterized by a nominal (i.e. calculated from the weighted amount of precursors) Zn/Mg atomic ratio of 0.01 (Accession #1189), 0.1 (Accession #1190), 0.25 (Accession #1191), and 0.5 (Accession #1192). The surface properties and the influence of the Zn/Mg atomic ratio are investigated by means of XPS (using a standard Al K?). Besides the wide scan spectra, detailed spectra for the Mg 1s, Zn 2p3/2 and O 1s regions and related data are presented and discussed. XPS analysis confirms the presence of MgO and ZnO; the peak shapes are consistent with a more heterogeneous situation for the samples with lower Zn/Mg atomic ratios. The XPS Zn/Mg atomic ratio increases with increasing the nominal Zn/Mg atomic ratio reaching a plateau (of about 0.70) for the [Zn/Mg]nom = 0.25. The decrease of the O/(Mg+Zn) atomic ratio observed with increasing the Zn/Mg one (from 2.5 for [Zn/Mg]nom = 0.01 to 1.9 for [Zn/Mg]nom = 0.5) suggests a lower reactivity of ZnO with respect to atmosphere. This result is confirmed by the O 1s peak shape evolution. © 2010 American Vacuum Society.