Valence of vanadium in hydrated compounds

Abstract

Problems of the definition of vanadium chemical states in the mixed valency compounds are examined. The statistical analysis of the literature data on the values of binding energy and full width at half maximum (FWHM) of V 2p 3/2 peaks in different vanadium oxides is carried out.X-ray photoelectron spectroscopy was used to determine the chemical shift and FWHM of V 2p peaks of V 4+ and V 5+cations in the vanadium pentoxide matrix of hydrated vanadium compounds HV12O31·nH2O and (VO)V12O31·nH2O, prepared by using sol-gel technology. It was found that the binding energy of V 4+ ions shifts to the lower energy side of about 1.3 eV as compared to the main V 5+ ions in the matrix. The V 2p 3/2 line width for tetra-valent vanadium ions in xerogels is actually the same as for penta-valent ions.

XPS study of V1.67Ti0.33O5±δ·nH2O xerogels intercalated with hydroquinone

“…This fact shows that independent of the hydroquinone intercalation degree and Ar + ion etching the ions of titanium are in stable 4+ states. The similar stable states of Ti ions were observed in vanadium-titanium hydrates [14,15].…”

“…2 and 3). The binding energies of three V 2p 3/2 peak components are ∼517, ∼516, and ∼515 eV (see Tables 3 and 4) that correspond to 5+, 4+, and 3+ valence states of vanadium [13,[16][17][18]. The V 3+ ions exist in all investigated compounds before as well as after the Ar + ion bombardment.…”

Structure and Capacitive Properties of Porous Nanocrystalline VN Prepared by Temperature-Programmed Ammonia Reduction of V2O5

“…Great care, however, has to be exercised to determine the presence of vanadium in different oxidation states since the binding energies (BE) of V 2p 3 line (which is normally used) for vanadium oxides with various oxidation states of vanadium (V 2 O 5 , VO 2 , and V 2 O 3 , corresponding to V 5+ , V 4+ , and V 3+ ) are in a narrow range of about 515.5−517.5 eV . The situation is further complicated since a range of BE values is reported for each oxidation state of vanadium possibly because of equipment calibration differences and inaccuracy of the correction for sample charging …”

Hydrothermal synthesis of mesoporous rod-like nanocrystalline vanadium oxide hydrate V3O7·H2O from hydroquinone and V2O5

“…The V2p 3/2 peak of the sample is divided into two peaks at the binding energies of 518.41 and 516.79 eV (Fig. 6c), assigned to V 5+ and V 4+ , respectively [50][51][52]. The O1s peak could be divided into two nearly Gaussian components: which are low binding energy peak and high binding energy peak centered at around 530.62 and 532.62 eV, respectively (Fig.…”