Bipolar membrane polarization behavior with systematically varied interfacial areas in the junction region
Bipolar membrane polarization behavior with systematically varied interfacial areas in the junction region
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DOI：
10.1039/d0ta10602j
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发表时间：
2021-01-28
影响因子：
11.9
通讯作者：
Arges, Christopher G.
中科院分区：
文献类型：
--
作者：
Kole, Subarna;Venugopalan, Gokul;Arges, Christopher G.
双极膜(BPM)的应用范围最近已经扩展到电渗析之外，因为它们现在被考虑用于燃料电池和电解应用。它们在新兴的电化学技术中的应用源于需要一种膜分离器来提供不同的pH环境，并防止物种交叉。目前对BPM的材料研究主要集中在水解离催化剂方面，而对聚阳离子-聚阴离子界面的设计以改善BPM性能的研究较少。在这里，软光刻制造了一系列微图案化的BPM，精确地控制了双极结中的界面面积。极化实验表明，界面面积增加2.28倍，起始电位降低250 mV。此外，由于结区处于动力学扩散控制之下，界面面积的增加也使电流密度略有提高。一个基于结合区电场的简单物理模型合理地解释了水解离过电势作为界面面积的函数的降低。最后，软光刻方法也有利于制备从全氟聚合物骨架到碱性稳定的聚芳烃聚合物等不同化学成分的BPM。这些聚合物化学更适合于燃料电池和电解应用。以碱性稳定的聚三苯基阴离子交换膜为特征的BPM的起始电位为0.84V，接近热力学极限，比市售的BPM低约150 mV。
The palette of applications for bipolar membranes (BPMs) has expanded recently beyond electrodialysis as they are now being considered for fuel cell and electrolysis applications. Their deployment in emerging electrochemical technologies arises from the need to have a membrane separator that provides disparate pH environments and to prevent species crossover. Most materials research for BPMs has focused on water dissociation catalysts and less emphasis has been given to the design of the polycation-polyanion interface for improving BPM performance. Here, soft lithography fabricated a series of micropatterned BPMs with precise control over the interfacial area in the bipolar junction. Polarization experiments showed that a 2.28x increase in interfacial area led to a 250 mV reduction in the onset potential. Additionally, the same increase in interfacial area yielded marginal improvements in current density due to the junction region being under kinetics-diffusion control. A simple physics model based on the electric field of the junction region rationalized the reduction in the overpotential for water dissociation as a function of interfacial area. Finally, the soft lithography approach was also conducive for fabricating BPMs with different chemistries ranging from perfluorinated polymer backbones to alkaline stable poly(arylene) hydrocarbon polymers. These polymer chemistries are better suited for fuel cell and electrolysis applications. The BPM featuring the alkaline stable poly(terphenyl) anion exchange membrane had an onset potential of 0.84 V, which was near the thermodynamic limit, and was about 150 mV lower than a commercially available variant.