Preparation, characterization and proton-conductivity of silica gel containing 71 wt.% 12-tungstogermanic heteropoly acid

Silica gel containing 71 wt.% 12-tungstogermanic acid was prepared by means of sol–gel method. Infrared (IR) spectrum and X-ray powder diffraction (XRD) pattern revealed that the Keggin structure characteristic of GeW12O404− anion was present in the silica gel skeleton. The change of the characteristic peaks in the IR spectra was investigated. Thermogravimetry (TG) curve shows that there are three steps of weight loss. Differential thermal analysis (DTA) curve shows that the thermal stability of gel is lower than that of pure 12-tungstogermanic acid. The silica gel exhibited considerably high proton conductivity. It is 4.00 × 10−3 S cm−1 at room temperature (16°C).