Proton conducting composite materials containing heteropoly acid and matrices

The composite materials were prepared by 90 wt.% tungstovanadophosphoric heteropoly acids with Dawson structure (H7P2W17VO62·nH2O and H9P2W15V3O62·nH2O, abbreviated as P2W17V and P2W15V3), 5 wt.% silica gel (SiO2) and 5 wt.% organic polymers (polyvinylpyrrolidone, PVP or polyethylene glycol, PEG). The products were characterized by the infrared (IR), X-ray powder diffraction (XRD) and electrochemical impedance spectroscopy (EIS). EIS measurements show that the conductivity values PVP/P2W17V/SiO2, PVP/P2W15V3/SiO2 and PEG/P2W15V3/SiO2 are 1.89 × 10−2, 2.32 × 10−2 and 2.67 × 10−2 S cm−1 at 26 °C and 75% relative humidity, which increase with higher temperature. They exhibit low activation energies of 16.12, 16.85 and 14.02 kJ mol−1 for proton conduction, respectively. The mechanisms of proton conduction of the composite materials are also proposed.