PREPARATION AND PROTON-CONDUCTION OF SILICA-GELS CONTAINING HETEROPOLY ACIDS

Bulk silica gels containing dodecatungstophosphoric acid, H3PW12O40-29H2O (WPA) or dodecamolybdophosphoric acid, H3PMo12O40.29H2O (MPA), were prepared by the sol-gel method using tetraethoxysilane and each heteropoly acid. Infrared spectra of the gels revealed that the Keggin structure characteristic of heteropoly anions was present in the silica gel skeleton. WPA- or MPA-doped silica gels exhibited higher conductivities by more tan two orders of magnitude than the pure silica gel. Remarkable coloration was observed in the electrochromic cell using the WPA-doped silica gel as a solid electrolyte; the reversibility and response of the coloring and bleaching were comparable to the case using a typical liquid electrolyte of H2SO4.