Proton conductors stability

Conductivity of Nation in comparison to some intermediate-temperature proton conductors and the oxide ion conductivity of YSZ (yttria-stabilized zirconia). (From Kreuer, K. D. et al 2004. Chemical Reviews 104 4637-4678.)... 

It has been reported (4,5) that solid electrolyte sensors using stabilized zirconia can detect reducible gases in ambient atmosphere by making use of an anomalous EMF which is unusually larger than is expected from the Nernst equation. However, these sensors should be operated in a temperature range above ca. 300°C mainly because the ionic conductivity of stabilized zirconia is too small at lower temperatures. On the other hand, solid state proton conductors such as antimonic acid (6,1), zirconium phosphate (8), and dodecamolybdo-phosphoric acid (9) are known to exhibit relatively high protonic conductivities at room temperature. We recently found that the electrochemical cell using these proton conductors could detect... 

Stability issues The many stability issues discussed for ceramic oxygen-ion conductors apply also to proton conductors. Reactions with acidic gas components... 

Bhide, S.V. and Virkar, A.V., Stability of BaCeOj-based proton conductors in water-containing atmospheres, / Electrochem. Soc., 146, 2038-2044 (1999). 

Ammonium polyphosphate composite-based proton conductors for the intermediate temperature range (200°C-300°C) have been found to possess good proton conductivity (0.1 Scm at 300°C) under humidified conditions [147], This temperature range would not have any kinetics or CO poisoning problem, but improving stability of the proton conductor in fuel cell conditions is still a challenge [148-151]. 

Hashimoto, A., Hibino, T., Mori, K.-T. and Sano, M. (2001) High-temperature hydrocarbon sensors based on a stabilized zirconia electrolyte and proton conductor-containing platinum electrode. Sens. Actuators B, 81, 55-63. 

Bhide SV, Virkar AV. Stability of AB l/2B l/203-type mixed Perovskite proton conductors. 

Carneim RD, Armstrong TR. Chemical stability of Barium cerates-based high temperature proton conductors. 225th American Chemical Society National Meeting - Fuel Division Preprint, New Orleans, LA, 2003. 

Matsumoto H, Kawasaki Y, Ito N, Enoki M, Ishihara T. Relation between electrical conductivity and chemical stability of BaCe03-based proton conductors with different trivalent dopants. Electrochem. Solid-State Lett. 2007 10(4) B77. 

Fig. 4.4. Correlations between conductivity, thermal stability and O. .. O hydrogen bond distance for some protonic conductors hydrogen 3- and oxonium per-...

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