Synthesis, crystal structure and conductive mechanism of solid high-proton conductor tungstovanadosilicic heteropoly acid

Tungstovanadosilicic heteropoly acid H5SiW11VO40·15H2O has been successfully synthesized and characterized. The single crystal of this solid proton conductor was firstly obtained and the crystal structure was determined from single crystal X-ray diffraction. The complex crystallizes in the monoclinic system, space group C2/c, with a = 12.716(3) Å, b = 19.881(5) Å, c = 19.099(5) Å, α = 90°, β = 90.796°, γ = 90°, V = 4828(2) Å, Z = 4. Its proton conductivity was measured using electrochemical impedance spectroscopy (EIS) in the temperature range 15-55 °C, and the activation energy of the conductivity was determined. The results show that it has appreciable proton conductivity (7.93 × 10−3 S cm−1) at 15 °C and 50% relative humidity, with an activation energy of 21.59 kJ mol−1 for proton conduction. The conductive mechanism is Vehicle mechanism.