Modified electrodes based on mixed bentonite vanadium(V) oxide xerogels

A novel type of composite xerogel can be obtained by the combination of pol yvanadic acid and bentonite clay. displaying a characteristic green colour, associated with the presence of vanadium(IV) sites and intervalence-transf er bands in the near-infrared region. The slow evaporation of the xerogel s uspensions leads to lamellar solids containing vanadium(V) oxide and silica te layers. In contrast to the vanadium-oxide films, the composite xerogels are not soluble in water, showing a good electrochemical response when appl ied onto electrode surfaces. Enhanced electrochemical signals are observed in the presence of electroactive species such as the hexaammineruthenium(II ) complexes, reflecting their intercalation into the interlamellar space. ( C) 1999 Elsevier Science S.A. All rights reserved.