Determination of the V2p XPS binding energies for different vanadium oxidation states (V5+ to V0+)

The V2p and O1s XPS spectra of the vanadium oxides V2O5, VO2 and V2O3 were measured to determine the V2p XPS fit parameters, (binding energy (BE) and % Lorentzian–Gaussian) for the vanadium oxidation states V5+, V4+ and V3+. The VO2 and V2O3 powder pellets were over-oxidized and no V3+ state was observed. Therefore an Ar+ bombardment was given to the V2O3 to reduce the vanadium oxide and to obtain the V3+ state. An XPS fit procedure is presented on the basis of these spectra. This fit procedure includes the combined fitting of the V2p and the O1s signal. The binding energy of the V2p3/2 core level for each vanadium oxidation state is fixed relative to the O1s level. V2p satellite peaks were added to the fit especially for the lower vanadium oxidation states.