The interaction of a perfluorinated anion exchange membrane (AEM), initially in the hydroxide form, with atmospheric CO₂ at 60 °C and under a range of relative humidity conditions is studied both in a fuel cell and with ex situ measurements to understand the performance drop. A new novel titration method was used to quantify the amounts of hydroxide, carbonate and bicarbonate in the membrane. However, hydroxide and bicarbonate react internally which disturbs the equilibrium and hence it's impossible to detect real species concentration using titration. The uptake of CO₂ leads to a rise in membrane mass within the first 15 min. The anionic conductivity of the AEM experiences a quick drop within 20 minutes to carbonate and bicarbonate levels. However, switching the inlet gas to 0 ppm CO₂ reverses the equilibrium due to the desorption phenomenon. Investigating the morphology of the film by small angle X-ray scattering shows that the ionomer domains lose intensity as the reaction progresses, and the drop is of the double-exponential type but the time of equilibration is slower when compared to that of the conductivity. The wide-angle X-ray scattering data were fit to 3 Gaussian peaks showing that the CF₂ inter-chain spacing becomes less crystalline during the process. 30% of peak power was lost for this membrane in an AEM fuel cell on addition of CO₂, yet we observed the highest H₂/ambient air (400 ppm CO₂) performance, 446 mW cm⁻², reported to date.

中文翻译：

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深入了解空气中阴离子交换膜燃料电池的CO2限制

在燃料电池和异位测量中，研究了最初为氢氧根形式的全氟阴离子交换膜（AEM）与大气中的CO ₂在60°C和一系列相对湿度条件下的相互作用。下降。一种新的新型滴定法用于定量膜中氢氧化物，碳酸盐和碳酸氢盐的量。但是，氢氧化物和碳酸氢盐会在内部发生反应，从而干扰平衡，因此无法通过滴定法检测实际物质的浓度。吸收CO ₂导致前15分钟内膜质量增加。AEM的阴离子电导率在20分钟内迅速下降至碳酸盐和碳酸氢盐水平。但是，由于解吸现象，将进气转换为0 ppm CO ₂会使平衡逆转。通过小角度X射线散射研究膜的形貌表明，离聚物结构域随着反应的进行而失去强度，并且液滴是双指数型的，但是与电导率相比，平衡时间更慢。广角X射线散射数据拟合到3个高斯峰，表明CF ₂链间间距在该过程中变得较少结晶。添加CO时，该膜在AEM燃料电池中损失了30％的峰值功率_{如图2所示}，迄今为止，我们观察到最高的H ₂ /环境空气（400 ppm CO ₂）性能为446 mW cm ^-2。