High Proton Conductivity in Porous P₂O₅−SiO₂ Glasses

Abstract

High proton conducting P2O5−SiO2 glasses were prepared using the sol−gel method, the electrical conductivities of which were studied in relation to the pore structure and the adsorbed water. The pore properties of SiO2 and P2O5−SiO2 glasses were controlled by addition of formamide during the gel synthesis, the specific surface areas of which were changed from 200 to 900 m2/g-glass. These glasses absorb water molecules on exposure to a humid atmosphere. The conductivity increased with increasing logarithm of water concentration and reached a saturated value above the water vapor pressure of 0.8. The highest conductivity, 2 × 10-2 S/cm at room temperature, was achieved by 5P2O5−95SiO2 glass heated at 700 °C and absorbing the water molecules.

Hydrolytically Stable Phosphorylated Hybrid Silicas for Proton Conduction

“…Like pure silicas, the slow proton conduction observed for 1A2T is supposed to result from proton transfer between weakly protongenic Si-OH groups and water molecules. [39,40] As shown by Figure 8a, the conductivity increases with the increase in the content of APTES in hybrid silicas, where more phosphonic acid groups have been incorporated as confirmed by XPS analysis. Sample 2A3TP has the highest conductivity of all three phosphorylated samples, and is only about one times lower than Nafion 117.…”

Proton Conductivity of Mesoporous Silica Incorporated with Phosphorus under High Water Vapor Pressures up to 150.DEG.C.

“…This peak and shoulder were attributed to OH stretching. 5,19 This absorption peak with a shoulder was observed in the P 2 O 5 -SiO 2 glass prepared by reacting TMOP and TEOS, but not in the glass.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Proton conduction occurs through surface adsorbed water and condensed water in pores. The water vapor condenses in pores through capillary condensation, and this occurs at lower water vapor pressures for smaller pores.…”

“…Therefore, an increase in the acidity of the material surface by introducing strong acids is effective to enhance water dissociation and proton conduction. 1,[5][6][7][8][9][10][11][12][13] The phosphoric 1,5-12 and sulfonic 13 acid groups are generally used for silica derived materials. In addition, strong acidity also contributes to retaining water molecules under low water vapor pressures.…”

Effects of humidity on performance of electric-double-layer oxide-based thin-film transistors gated by nanogranular SiO2 solid electrolyte

“…The relative capacitance decreasing with the decrease in humidity can be explained by taking types of the densities into account, 18 which suggesting that the density of charge is reducing gradually. Because when in high relative humidity environment, hydroxyapatite groups (-OH) 19 are formed in nanogranular SiO 2 solid electrolyte by chemisorptions of H 2 O molecules, so the proton concentration and the speed of proton conduction could be improved, leading to the augment in the density of charge. To the contrary, with the relative humidity decreasing, less and less H 2 O molecules permeate to the nanogranular SiO 2 solid electrolyte, which gradually leading to less protons accumulation and electrochemical reaction, so the density of charge is reducing gradually.…”