Abstract

New layered vanadium oxides were prepared at room temperature via either electrochemical or chemical topotactic oxidation in aqueous media of the layered, solid precursor H₂V₃O₈. Their formula M_yH_1 − yV₃O₈·nH₂O (M = Li, Na, K) shows the oxidation of vanadium to occur with the removal of one hydrogen atom and with a partial exchange of the remaining proton. A structural study by powder X-ray diffraction, including a Rietveld analysis, clearly indicated that the structure of the anionic covalent layers, V₃O₈, are preserved in going from H₂V₃O₈ to M_yH_1 − yV₃O₈·nH₂O. In the latter compounds, all the water molecules occupy the interlayer space along with the M⁺ ions.