A Study of Carbonate Formation Kinetics and Morphological Effects Observed on OH~- form of Pfaem When Exposed to Air Containing CO_2

摘要

For AEMFC, OH~- form of membrane reacts with CO_2 when exposed to air leading to loss in conductivity. Very few attempts have been made to understand the reaction kinetics, morphological properties and equilibrium concentrations at different environmental conditions. We have attempted to study the CO_2 kinetics and its effect on water-uptake (or lambda) and morphology (SAXS) when the OH~- form of membrane is exposed to air which has approx. 400 ppm of CO_2. The kinetics was studied by exposing the membrane to controlled environment and titrating it using Warder and Winkler titration methods. From transient SAXS analysis we observe the intensity of ionomer feature of membrane spectrum dropping over time. Also the d-spacing at equilibrium is lower than the initial value. Ultimately we want to understand the effect of CO_2 on membrane from every aspect and possibly help us think about strategies to mitigate the problem.