Al-Dhubhani Emad, Tedesco Michele, de Vos Wiebe M, Saakes Michel
Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands.
Membrane Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
ACS Appl Mater Interfaces. 2023 Oct 4;15(39):45745-45755. doi: 10.1021/acsami.3c06826. Epub 2023 Sep 20.
Electrospinning has been demonstrated as a very promising method to create bipolar membranes (BPMs), especially as it allows three-dimensional (3D) junctions of entangled anion exchange and cation exchange nanofibers. These newly developed BPMs are relevant to demanding applications, including acid and base production, fuel cells, flow batteries, ammonia removal, concentration of carbon dioxide, and hydrogen generation. However, these applications require the introduction of catalysts into the BPM to allow accelerated water dissociation, and this remains a challenge. Here, we demonstrate a versatile strategy to produce very efficient BPMs through a combined electrospinning-electrospraying approach. Moreover, this work applies the newly investigated water dissociation catalyst of nanostructured silica MCM-41. Several BPMs were produced by electrospraying MCM-41 nanoparticles into the layers directly adjacent to the main BPM 3D junction. BPMs with various loadings of MCM-41 nanoparticles and BPMs with different catalyst positions relative to the junction were investigated. The membranes were carefully characterized for their structure and performance. Interestingly, the water dissociation performance of BPMs showed a clear optimal MCM-41 loading where the performance outpaced that of a commercial BPM, recording a transmembrane voltage of approximately 1.11 V at 1000 A/m. Such an excellent performance is very relevant to fuel cell and flow battery applications, but our results also shed light on the exact function of the catalyst in this mode of operation. Overall, we demonstrate clearly that introducing a novel BPM architecture through a novel hybrid electrospinning-electrospraying method allows the uptake of promising new catalysts (i.e., MCM-41) and the production of very relevant BPMs.
静电纺丝已被证明是一种非常有前景的制备双极膜（BPM）的方法，特别是因为它能够实现阴离子交换纳米纤维和阳离子交换纳米纤维的三维（3D）缠结连接。这些新开发的双极膜适用于多种苛刻的应用，包括酸碱生产、燃料电池、液流电池、氨去除、二氧化碳浓缩和氢气生成。然而，这些应用需要将催化剂引入双极膜以加速水的离解，而这仍然是一个挑战。在此，我们展示了一种通用策略，通过静电纺丝-电喷雾相结合的方法制备非常高效的双极膜。此外，这项工作应用了新研究的纳米结构二氧化硅MCM-41作为水解离催化剂。通过将MCM-41纳米颗粒电喷雾到与双极膜主要3D连接直接相邻的层中制备了几种双极膜。研究了具有不同MCM-41纳米颗粒负载量的双极膜以及相对于连接点具有不同催化剂位置的双极膜。对这些膜的结构和性能进行了仔细表征。有趣的是，双极膜的水解离性能显示出明显的最佳MCM-41负载量，此时其性能超过了商业双极膜，在1000 A/m时记录的跨膜电压约为1. Volt。这种优异的性能与燃料电池和液流电池应用高度相关，但我们的结果也揭示了催化剂在这种操作模式下的确切功能。总体而言，我们清楚地证明，通过新颖的混合静电纺丝-电喷雾方法引入新颖的双极膜结构能够采用有前景的新型催化剂（即MCM-41）并制备出非常适用的双极膜。
