There are some reports about the analyzing of the average chemical valence by titration. However, the results obtained from this method strongly depended on the operator and this is also a time-consuming job. Many researches indicated that the chemical state of vanadium is XPS(X-ray photoelectron spectroscopy) sensitive. And now, a large amount of XPS data for chemicals with V5þ,V4þ, V3þ and V0 are available in literature [37–39]. Silversmit et al. [40] proposed a method to determinate different vanadium oxidation states by detecting theV2p XPS binding energies. Fig. 3 showed the XPS spectra for samples corresponding to Fig. 2 which were fabricated by the slight variation of molar ratio from the proper value. TheO1s core level centred at 530.0eV was used as an internal binding energy reference and energy gaps between the binding energies of the V2p32 core level for each vanadium oxidation state and the reference could be calculated. It could be found that the energy gap became higher with the increase in oxidation states of vanadium. This trend was consistent with Silversmit et al.’s [40] results.