Speaker
Description
Proton exchange membrane water electrolyzers (PEMWEs) face performance limitations due to the poor interfacial contact between the catalyst layer and the porous transport layers (PTLs). This issue reduces catalyst utilization and increases contact resistance, leading to non-uniform exposure to applied voltages or currents. Such non-uniformities not only lower efficiency but also accelerate catalyst degradation. While increasing anode catalyst loadings can partially address these challenges, doing so conflicts with efforts to minimize the use of precious metals to reduce system costs. Additionally, the poor in-plane conductivity of anode catalysts further aggravates these limitations. Micro-porous layers (MPLs) have emerged as a promising solution to these interfacial challenges. By providing high surface area and small pore sizes, MPLs can significantly improve contact with the catalyst layer, enhancing catalyst utilization and reducing contact resistance. Furthermore, the hierarchical structure of MPLs facilitates more effective oxygen removal and improves water transport to the anode catalyst layer, addressing mass transport limitations and supporting stable operation.
In this study, titanium-based MPLs were fabricated through electrospinning, using a titanium precursor and a carrier polymer. Electrospinning was chosen due to its superior control over fiber morphology and uniformity. The resulting electrospun fibers were calcined to produce TiO₂ fibers, forming the MPL structure. To ensure robust integration, the MPL was incorporated into a commercial felt-based PTL substrate using hot-pressing and sintering techniques. This approach aimed to optimize the physical and electrical connections between the MPL and the PTL substrate, enhancing overall performance.
Electrochemical performance of the MPL-PTL assemblies was evaluated through polarization curves, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry. These analyses provided insights into the improvements in catalyst utilization, contact resistance, and mass transport properties achieved by integrating MPLs. Surface characterization of the MPL and catalyst layer was performed before and after electrolyzer testing using scanning electron microscopy (SEM) and laser profilometry. These techniques revealed structural and morphological changes, further highlighting the effectiveness of MPLs in improving interfacial properties and durability. This study demonstrates that titanium-based MPLs offer a viable pathway to address interfacial limitations in PEMWEs. By improving integration and enhancing transport properties, these MPLs have the potential to reduce catalyst loading requirements while maintaining or even improving performance, thereby contributing to the development of more cost-effective and durable electrolyzer systems.
Acknowledgements
This research is supported by the U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office through the Hydrogen from Next-generation Electrolyzers of Water (H2NEW) consortium. Program manager Dave Peterson and Mackenzie Hubert.
| Country | United States |
|---|---|
| Acceptance of the Terms & Conditions | Click here to agree |
