Topotactic redox reactions and ion exchange of layered MoO3 bronzes

Chemical or electrochemical reduction of MoO3 in neutral aqueous electrolyte solutions results in the reversible topotactic formation of a new type of molybdenum oxide bronzes A+x(H2O)y[MoO3]x−. The latter are built up by negatively charged [MoO3]x− layers with exchangeable hydrated cations in the interlayer space. Non-solvated cations are taken up between the MoO3 sheets on cathodic reduction of the oxide in organic electrolyte solutions. Galvanostatic studies on the reduction of MoO3 in aqueous acids reveal the strong influence of kinetics on hydrogen ion uptake. Earlier results of Glemser (2) on "genotypic" hydrogen bronzes of MoO3 are confirmed. H0.5MoO3 was found to exhibit Brönsted acid character and to form a novel type of layer intercalation compounds LxH0.5MoO3 with Lewis bases.