Performance improvement induced by membrane treatment in proton exchange membrane water electrolysis cells

Hydrogen has been widely accepted as the best alternative energy carrier to store intermittent renewable energies. Proton exchange membrane water electrolysis (PEMWE) represents a promising technology to produce highly pure hydrogen with high efficiency and low footprint. While great progress has been made on components, materials and even fabrication processes, new materials or complicated processes still require refinement in the process of continuously improving PEMWE performance and durability. In this study, we demonstrate a facile treatment on membranes, aiming at improving cell performance at low costs. By adopting the hydration in DI water or 0.5 M H2SO4, or by varying the treatment sequence with the catalyst layer deposition, the PEMWE performance was tuned with the overpotential improvement as high as 50 mV at 2.0 A cm(-2). The PEMWE cells after different treatments were characterized both ex-situ and in-situ, and the mechanism was also proposed. The H2SO4 treatment swelled the micro micelle structure of the Nafion membranes, resulting in a higher proton conductivity and better cell performance compared with those from DI water treatment. In addition, the treatment sequence also had great impact, and the treatment after the catalyst layer deposition would result in better performance due to the reduced resistance and better kinetics. Not only the types of membrane, but also the thickness should be measured and reported when tested, which is more critical when compared across the published works from different groups. This work could also provide a guideline for future membrane treatment and PEMWE cell testing. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved