Preparation and proton-conduction of silica gels containing heteropoly acids

Abstract

Bulk silica gels containing dodecatungstophosphoric acid, H 3PW 12O 40·29H 2O (WPA) or dodecamolybdophosphoric acid, H 3PMo 12O 40·29H 2O (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 H 2SO 4.