Synthesis and high proton conductive performance of a quaternary vanadomolybdotungstosilicic heteropoly acid

Abstract

A new vanadium and molybdenum-substituted quaternary silicon-containing heteropoly acid H₆SiW₉MoV₂O₄₀·15H₂O has been synthesized in this paper by the stepwise acidification and the stepwise addition of elemental solutions. The structural feature and hydration of this product were characterized by IR, UV, XRD and TG-DTA, and its proton conductivity was measured by electrochemical impedance spectroscopy (EIS). The result of EIS shows that H₆SiW₉MoV₂O₄₀·15H₂O is a solid high-proton conductor with a conductivity of 6.01 × 10⁻³ S cm⁻¹ at 22 °C and 80% relative humidity, which increases at higher temperatures. Its conductive activation energy is 27.5 kJ mol⁻¹, which suggests that the mechanism of proton conduction is dominated by the vehicle mechanism.