Xerogels electrochemical oxidation

The double layers of vanadium oxide found in the xerogel have been described in a number of other vanadium oxides by Galy ° and Oka ° they also form the double sheets described above for VeOis. These oxides, in which the vanadium is found in distorted VOe octahedra, show particularly attractive electrochemical capacities " exceeding 200 mAh/g in some cases, as shown in Figure 9. However, at the present time their rate capability appears somewhat limited. More recently vanadium oxide nanotubes have been synthesized, first by Spahr et these compounds also contain double sheets of vanadium oxide and again have interesting but complex... 

Spectroelectrochemical analysis of charge-insertion nanostructured materials already offers important insight into these systems. These methods were recently exploited to characterize the electrochemical processes of nanostructured manganese oxide ambi-gel and xerogel films. " 6-229 Spectroelectrochemical measurements were used to corroborate electronic state changes with the observed electrochemical response for the insertion of small cations (Li+, Mg2+) and the unexpected insertion of a bulky organic cation (tetrabutylammonium). Vanadium pentoxide exhibits two distinct electrochromic features that can be assigned to the transition at either sto-... 

Fe(III) is observed and revealed by Mossbauer spectroscopy. This unique behaviour is indicative of a particular substructure in the gel where ferrocene units are mainly located at the surface of the material. A completely different situation is observed for the bi-silylated xerogel obtained from 102 for which a Cottrelian charge transfer is observed and it exhibits a classical reversible voltammogram the peak current scales linearly with the square root of scan rate. Moreover, it is impossible to achieve a complete Fe(II)/Fe(ni) oxidation although the process is still reversible. Such behaviour demonstrates that some of the ferrocenyl units are not accessible and do not participate in the electrochemical process103. 

F. J. Anaissi, G. J.-F. Demets, E. B. Alvarez, M. J. Politi, and H. E. Toma, Long-term aging of vanadium (V) oxide xerogel precursor solutions structural and electrochemical implications, Electrochim. Acta, 47, 441 50 (2001). 

C. Lin, J. A. Ritter, and B. N. Popov, Development of Carbon-Metal Oxide Supercapacitors from Sol-Gel Derived Carbon-Ruthenium Xerogels, J. Electrochem. Soc., 146, pp. 3155-60, 1999. 

Lin C, Ritter JA, Popov BN (1999) Development of carbon-metal oxide supercapacitors liom Sol-Gel derived carbon-mthenium xerogels. J Electrochem Soc 146 3155... 

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