INTERFACE PROPERTIES OF VANADIUM PENTOXIDE GELS

Strong correlations are observed between delocalized unpaired electrons and adsorbed water molecules in vanadium pentoxide gels V2O5,nH2O. These gels exhibit a layered structure but both the amount of water molecules and the basal distance increase when the number of reduced V(IV) ions increases. Hydration and dehydration cycles lead to a spontaneous reduction of the oxide. These features could be due to some electron localization on protonated vanadium sites at the oxide/water interface. Solute [VO(H2O)5]++ species are then removed from the surface of the oxide phase and intercalated into the interfoliar space of the gel. Such electron-proton interfacial interactions seem to be quite general in mixed valence oxide colloidal solutions.