Electrochemical and Microstructural Analysis of a Modified Gas Diffusion Layer for a PEM Water Electrolyzer

• Published in: International journal of electrochemical science Vol. 15; no. 6; pp. 5571 - 5584
• Main Authors: Cruz, J.C., Barbosa, R., Escobar, B., Zarhri, Z., Trejo-Arroyo, D.L., Pamplona, B., Gómez-Barba, L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2020
• Subjects: Gas Diffusion Layer; Microstructural Analysis; Microstructural Attack; Porous Matrix; Water Electrolysis; Water Electrolysis; Gas Diffusion Layer; Microstructural Attack; Microstructural Analysis; Porous Matrix
• ISSN: 1452-3981; 1452-3981
• DOI: 10.20964/2020.06.12

Water electrolysis is an electrochemical process capable of producing high-purity hydrogen (H2 ≈ 100%). However, due to high anodic operating potentials, which are greater than 1.8 V in acidic media, they tend to degrade the components that are currently designed. One of the main components is the gas diffusion layer (GDL) of a proton exchange membrane water electrolyzer (PEMWE). A commonly used carbon GDL is coal. However, the acid medium increases the potential to 1.4 V, which causes the GDL to become oxidized and degrade; the above result is due to the generation of carbon products that poison the electrode and the blocking of active sites, all of which decrease the performance of the cell. In this work, the results of a morphological study on a modified titanium porous matrix are presented. The analysis includes the determination of the microstructural influence on mass transport through numerical simulation and statistical electrochemical characterization techniques. Two different microstructural attacks are performed to modify the porous matrix. These attacks consist of an acidic mixture of 17 and 27% v/v HCl/H2SO4 and an attack by a 0.1 M oxalic acid solution; these attacks were performed at different times. Afterward, the GDLs were characterized by scanning electron microscopy (SEM) at different magnifications to determine significant microstructural differences between the three matrices (the two that are modified and the one without modification) and their stochastic reconstruction. Subsequently, a surface area characterization is performed by the BET absorption technique to calculate the porosity of the different matrices.