Preparation of Proton‐Conducting Amorphous Films Containing Dodecamolybdophosphoric Acid by the Sol—Gel Method

Silica gel films containing dodecamolybdophosphoric acid, H3PMo12O40·29H2O (MPA), were prepared by the sol—gel method. Amorphous films were obtained for the compositions with 0 to 42 wt% MPA. Infrared spectra revealed that the skeleton of heteropolyanions PMo12O3−40 remained in the silica gel structure. The gel films exhibited considerably high proton conductivities in a highly humid atmosphere, and the conductivity increased with increasing MPA content. The value of conductance (G) at 1 kHz for these films was very sensitive to the variation of relative humidity (rh). The relation between log G and rh was almost linear and was reproducible on repeated runs for the gel films with 42 wt% MPA heat-treated at 200°C.