Acidity and catalytic activity of Nafion-H

Abstract

We thank Dr. Grot for providing us with an English language version of this paper. (12) Prolonged heating (10-50 h) was required to reach constant weight, and it seems likely that the reference states chosen by some of the previous workers do not represent equilibrium. Above about 200 °C extensive decomposition occurred.

Proton mobility in hydrated sulfonated polystyrene

“…The chemical shift value of these groups is higher in PS-SH III than in PS-SH II samples, suggesting that acidity is higher in PS polymers with an increasing amount of sulfonic groups. For long hydration times, chemical shift values of sulfonic groups approach those of water [37]. Fig.…”

“…Effect of the hydration time on the sample weight and NMR integrated intensities of sulfonic groups for PS-SH II and PS-SH III ionomers. [37]. This interaction explains the fast absorption of water produced at short times Table 3 shows the decrease in chemical shift value (δ H + ) of the proton signal in the sulfonic groups produced by the sample hydration.…”

“…The absence of any specific band ascribed to water molecules in 1 H NMR spectra suggests the existence of rapid exchanges between the sulfonic group protons and the water molecules [39]. In analyzed samples, chemical shift values, δ H , can be expressed as: [37].…”

Low-temperature operation of H2/O2 fuel cells using proton-conducting glasses containing heteropolyacid

“…Phosphotungstic acid (PWA) was successfully employed as the electrolyte in H 2 /O 2 fuel cells [3], as well as a surface promoter for CO-electro-oxidation [4]. Electrolyte material in polymer electrolyte fuel cells needs to have (a) high specific conductivity, (b) good mechanical and chemical stability, and (c) low cost [5,6]. Despite the increased proton conductivity, the alkaline phosphate glasses derived from sol-gel process have a limited phosphate concentration due to the decrease in mechanical strength and chemical stability with increasing phosphorus concentration [7,8].…”

Inherent Acidity of Perfluorosulfonic Acid Ionomer Dispersions and Implications for Ink Aggregation

“…In the cast state, it is well documented that PFSA is a solid superacid, with the sidechain pKa reported to be around -6. 36 It is expected that PFSA will also have some acidity in the dispersion state. This inherent acidity is vitally important for understanding the electrostatic interaction in ink systems, because electrostatic repulsion is a function of surface charge, or zeta potential (ζ), and it is well documented that ζ is a strong function of pH (for the case where protons are potential determining ions, which is true for nearly all systems).…”