Proton Conductivity in Zr ⁴⁺ ‐Ion‐Doped P ₂ O ₅ –SiO ₂ Porous Glasses

Abstract

The effect of zirconium ions on glass structure and proton conductivity was investigated for sol‐gel‐derived P 2 O 5 –SiO 2 glasses. Porous glasses were prepared through hydrolysis of PO(OCH 3 ) 3 , Zr(OC 4 H 9 ) 4 , and Si(OC 2 H 5 ) 4 . Chemical bonding of the P 5+ ions was characterized using 31 P‐NMR spectra. The phosphorous ions, occurring as PO(OH) 3 in the ZrO 2 ‐free glass, were polymerized with one or two bridging oxygen ions per PO 4 unit with increased ZrO 2 content. The chemical stability of these glasses was increased significantly on the addition of ZrO 2 , but the conductivity gradually decreased from 26 to 12 mS/cm at room temperature for 10P 2 O 5 ·7ZrO 2 ·83SiO 2 glass. A fuel cell was constructed using 10P 2 O 5 ·5ZrO 2 ·85SiO 2 glass as the electrolyte; a power of ∼4.5 mW/cm 2 was attained.