Speaker
Description
Wettability of gas diffusion layers (GDLs) plays a key role in liquid water transport and water management in polymer electrolyte fuel cells (PEFCs), yet its experimental determination remains challenging due to the complex, fibrous pore structure of these materials.1,2 Heterogeneous surface chemistry, comprising bare carbon and hydrophobically treated regions, combined with an anisotropic pore network, lead to reported contact angle values that vary widely across the literature, reflecting both the multiscale nature of GDLs and the diversity of measurement techniques used to probe wettability.3 This variability complicates comparison of experimental results and consistent parameterization of capillary transport models.
In this contribution, we apply a multiscale approach for wettability determination in GDLs that combines surface-based methods, bulk characterization techniques, and pore-scale imaging. Surface-sensitive techniques such as sessile drop and Wilhelmy balance measurements are used to probe the local or effective surface wettability1, while bulk methods like capillary pressure–saturation (pc–S) measurements are applied to characterize the wettability indirectly through capillary-driven transport behavior.3–5 Complementarily, imaging techniques provide direct insight into wetting behavior within the GDL microstructure, with X-ray tomography (XTM) enabling three-dimensional visualization of liquid water distributions and liquid–solid interfaces inside fibrous networks, allowing extraction of internal contact angles 6,7. This image-based derivation of capillary pressure–saturation relationships further links pore-scale wetting states to macroscopic capillary behavior, while pore-network analysis supports interpretation of invasion patterns and effective wettability parameters8.
This comparison of surface-based measurements, bulk uptake experiments, and XTM-derived metrics highlights the scale dependence of wettability measurements and emphasizes the need to interpret contact angles and related wetting parameters in the context of the underlying measurement principle. As such, the presented multiscale perspective provides guidance for selecting and interpreting wettability characterization methods for GDLs and supports an improved understanding of wettability phenomena in polymer electrolyte fuel cells.
| Country | Switzerland |
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| Student Awards | I would like to submit this presentation into the Earth Energy Science (EES) and Capillarity Student Poster Awards. |
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