Intercalation mechanism of nitrogenated bases into V2O5 xerogel

Abstract

It has been shown by i.r. and XPS techniques that protonation of nitrogenated bases (ammonia, pyridine and pyrazine) is the major process that occurs on adsorption of these compounds in the intracrystalline environment of V₂O₅· 1.5 H₂O xerogel. At room temperature the intercalation process takes place mainly by a proton-transfer reaction involving protons inherent to the solid and interlayer water molecules. Thermal treatment of the intercalated compounds gives rise to coordination of guest species to vanadium ions included in the host lattice, and V^V/–V^IV transformations are found to different extents depending on the nature of the intercalated molecules. The protons of the solid and the interlayer water appear to be the origin of the protonic conductivity on the V₂O₅· 1.5 H₂O xerogel, as shown by the impedance spectra. The V⁵⁺/V⁴⁺ couples formed in the intercalation process produce the electronic conductivity detected when the bases are intercalated in the layered solid.