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1741897 
Journal Article 
Study of vanadium(IV) species and corresponding electrochemical performance in concentrated sulfuric acid media 
Wu, X; Wang, J; Liu, S; Wu, X; Li, Sha 
2011 
Yes 
Electrochimica Acta
ISSN: 0013-4686 
56 
27 
10197-10203 
WOS:000297399100070 
The vanadium(IV) ion is found to form the [VO(SO(4))(H(2)O)(4)]center dot H(2)O complex, as well as the dimer, [VO(H(2)O)(3)](2)(mu-SO(4))(2), in concentrated H(2)SO(4) media. Their formation mechanisms were investigated by UV-Visible spectroscopy (UV-Vis), Raman spectroscopy, X-ray diffraction (XRD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). UV-Vis spectroscopy study showed that [VO(SO(4))(H(2)O)(4)]center dot H(2)O concentration in H(2)SO(4) solution was proportional to concentrations of VO(2+) and SO(4)(2-). The increased deviation from the near centrosymmetry of the octahedral complexes is due to the replacement of an equatorial water oxygen in [VO(H(2)O)(5)]SO(4) by a sulfate oxygen in [VO(SO(4))(H(2)O)(4)]center dot H(2)O. The dimer shows symmetrical structure, which correlates very well with non-activity in UV-Vis spectroscopic analysis. Structural information on both vanadium(IV) species can be confirmed by Raman and XRD measurements of crystals from the supersaturated solution of VOSO(4) in 1 M, 6 M and 12 M sulfuric acid. A solution of vanadium(IV) (0.05 M) in 12M H(2)SO(4), in which the vanadium(IV) species is [VO(H(2)O)(3)](2)(mu-SO(4))(2), exhibits a reversible redox behavior near 1.14V (vs. SCE) on the carbon paper electrode. (C) 2011 Elsevier Ltd. All rights reserved. 
Vanadium(IV) species; Reversible redox behavior; UV-Visible spectrum; Raman; Vanadyl sulfate hydrate