Advanced Porous-Transport-Layer Interface Design for PEM Electrolyzers

Abstract

Proton-exchange-membrane (PEM) water electrolyzers are promising technologies for generating clean hydrogen for use in a variety of sectors. The anode catalyst layer/porous-transport layer (CL/PTL) interface plays a vital role in determining performance of proton-exchange-membrane (PEM) water electrolyzers. This interface impacts ohmic, kinetic, and mass-transport overpotentials experienced by the cell. PTLs with large surface pores cause undesired catalyst layer deformation into pores of the PTL, which exacerbates degradation, and leads to high ohmic and kinetic overpotentials due to insufficient interfacial contact area.1,2 On the other extreme, low surface porosity at the interface leads to accumulation of oxygen gas that inhibit water transfer, resulting in mass-transport overpotentials.3 Thus, ideal PTLs should have hierarchical structure with high bulk porosity and low tortuosity to mitigate mass-transport overpotentials, while low surface porosity is need to enhance interfacial contact area. In this talk, we explore controlling the interfacial pore structure of these layers through a subtractive method, namely, laser ablation. Laser ablation is a facile method for tailoring the interfacial pore structure of PTLs. Heat from the laser melts titanium, granting a unique morphology advantageous to electrolyzer performance. Laser-ablated PTLs provide improved contact with the CL, while maintaining the bulk pore structure elsewhere, thereby facilitating gas removal and water transport. We also examine how laser-modified PTLs can help enable ultra-low catalyst loadings by minimizing interfacial contact resistance with the thinner catalyst layers. Overall, our work reveals that laser ablation is a facile method to enhance PEM electrolyzer performance. Acknowledgements This work was funded under the H2NEW Consortium by the Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office, of the U. S. Department of Energy under contract number DE-AC02-05CH11231. References T. Schuler, R. De Bruycker, T. J. Schmidt, and F. N. Büchi, J. Electrochem. Soc., 166, F270–F281 (2019)T. Schuler, T. J. Schmidt, and F. N. Büchi, J. Electrochem. Soc., 166, F555–F565 (2019).X. Peng et al., Adv. Sci., 8 (2021).