Synthesis, crystal structure and conductive performance of tungstovanadophosphoric heteropoly acid H4PW11VO40·8H2O

Tungstovanadophosphoric heteropoly acid H4PW11VO40·8H2O with Keggin structure has been synthesized by the stepwise acidification and the stepwise addition of element solutions. The optimal proportion of component compounds and pH value in the synthesis reaction were given. The crystal structure was determined from single crystal X-ray diffraction. The complex crystallises in the space group I-4, with a = 18.7648(9) Å, b = 18.7648(9) Å, c = 14.5762(9) Å, α = 90°, β = 90°, γ = 90°, V = 5132.5(6) Å, Z = 2. The product possesses Keggin structure and its conductivity was 1.50 × 10−2 S cm−1 at 26 °C and 75% relative humidity by electrochemical impedance spectroscopy (EIS) measurement, with an activation energy of 25.66 kJ mol−1 for proton conduction. The mechanism of proton conduction for this compound is vehicle mechanism.

► The single crystal of a solid proton conductor was firstly obtained.
► The conductivity of H4PW11VO40·8H2O is 1.50 × 10−2 S cm−1 at 26 °C and 75% RH.
► The mechanism of proton conduction of H4PW11VO40·8H2O is vehicle mechanism.