Abstract:

Bipolar membranes (BPMs) with a unique "sandwich" structure are a particular class of ion-exchange membranes. Under reverse bias, the unique water dissociation (WD) feature and the local pH control extensively apply the BPMs in acid/base production, resource separation and recovery. The WD resistance can be effectively reduced via the introduction of catalyst at the interfacial layer (IL) of BPMs. However, due to the imperfections of the IL, most BPMs have unwanted behaviors, such as high WD voltage, severe membrane delamination, catalyst leakage and high limiting current density, which leads to the large-scale industrial application of BPMs being unachievable. Therefore, based on the latest research progresses of BPMs, beginning with the WD mechanism of BPMs, this paper reviewed the research progress in three aspects: the types of interfacial layer catalyst, the construction methods of IL and the composite process of the membrane layers. Also, this paper deeply analyzed the merits and demerits of interfacial catalyst fixation methods such as immersion method, coating method, electrostatic assembly, in-situ growth and layer stacking, striving to provide corresponding theoretical support for the large-scale preparation of BPMs. Moreover, this paper also pointed out the bottleneck problem of BPMs and the crucial role of asymmetric BPM electrodialysis in industrial acid and base production. Finally, it was expected to explore the electrochemical application of BPMs, that was, efforts should be made to explore the application of BPMs in energy fields such as hydrogen generation by water electrolysis, carbon dioxide reduction, electrochemical synthesis of ammonia, fuel cells and liquid flow batteries, etc, so as to facilitate the evolution of BPMs.

Key words: bipolar membrane, interfacial layer, catalyst, water dissociation, electrochemical application

摘要：

双极膜是一类具有特殊“三明治”结构的离子交换膜。在反向偏压下，双极膜界面层独特的水解离行为使其具有在线生成H⁺和OH^-能力，因而在酸碱生产、资源分离回收等领域发挥着越来越重要的作用。双极膜界面层催化剂的引入可以有效降低水解离反应电阻。然而，大部分双极膜由于界面层构筑不当使其存在水解离电压过高、膜层结合力差、催化剂泄漏以及第一极限电流密度大等问题，无法实现大规模的工业化制备及应用。因此，本文立足于双极膜及技术近期研究进展，从双极膜的水解离机理出发，综述了界面层催化剂的种类、界面构筑方式及膜层的复合工艺三个方面的研究进展，深度分析了浸蘸法、涂覆法、静电组装、原位生长、层层堆叠等界面催化剂固定方式的优缺点，力求为双极膜的规模化制备提供相应的理论支撑。文中也指出了双极膜在工业化酸碱生产过程中的瓶颈问题，提出了不对称双极膜电渗析在工业化酸碱生产应用中的关键作用。最后对双极膜的电化学应用前景进行了展望，即应该努力探索双极膜在电解水制氢、二氧化碳还原、电化学合成氨、燃料电池、液流电池等能源领域的应用前景，以此来推动双极膜的发展。

关键词: 双极膜, 界面层, 催化剂, 水解离, 电化学应用