2D Model Porous Transport Layers for Interfacial Characterization in Polymer Electrolyte Water Electrolysis

Polymer electrolyte water electrolysis (PEWE) is a key technology in the realization of a future hydrogen economy. The thorough understanding and optimization of each of its components in a synergistic matter is essential in the advancement of this technology. In this study, we aim at understanding the role of the porous transport layer (PTL) interface in contact with the catalyst layer (CL) [1] and its impact on PEWE performance losses. We addressed the PTL/CL interface by creating a matrix of well-defined two-dimensional PTL materials [2]. These 2D-PTLs are fabricated by precise laser drillings of varying sizes on thin Ti-sheets, allowing us to accurately control geometrical properties such as interfacial contact area, pore size, triple-phase boundaries (TPB), and surface roughness. This systematic approach, combined with in-depth electrochemical analysis, provides insights into how the interface parameters affect the catalyst layer utilization at different current densities leading to severe differences in mass transport losses. Furthermore, by combining operando X-ray tomographic microscopy [3] and electrochemical characterization under selective conditions, we were able to get insights into the water transport mechanism inside the CL as a function of the different interfacial regions at the PTL/CL interface. The findings related to this work will potentially contribute to a future more rational design of PTL and CL structures. [1] T. Schuler, T.J. Schmidt, F.N. Büchi, J. Electrochem. Soc. 166 (2019) F555–F565. [2] Z. Kang, J. Mo, G. Yang, S.T. Retterer, D.A. Cullen, T.J. Toops, J.B. Green Jr, M.M. Mench, F.-Y. Zhang, Energy Environ. Sci. 10 (2017) 166–175. [3] S. De Angelis, T. Schuler, M.A. Charalambous, F. Marone, T.J. Schmidt, F.N. Büchi, J. Mater. Chem. A 9 (2021) 22102–22113. Figure 1