Initial Degradation Issues in AEMWE and the Importance of Catalyst/Ionomer Binding

Abstract

With the recent development of highly alkaline stable anion exchange membranes (AEMs) and ionomers (AEIs), anion exchange membrane water electrolyzer (AEMWE) has garnered attention due to its ability to achieve high hydrogen production rate at a low cost. The performance of AEMWE is determined by the anode catalyst layer, which can be made up of either a mixture of metal nanoparticles and polymer binders or a single metal. Although the integral metal has high mechanical properties, its performance is limited due to low electrochemical surface area and difficulties in mixing with binders, which makes it unsuitable for use in pure water. Catalyst layers made up of a combination of metal nanoparticles and polymeric binders can achieve high performance with a large surface area, but they often have low durability due to detachment of the anode catalyst layer from the porous transport layer substrate during water electrolysis. To prevent this, the anode catalyst layer must have high physical stiffness and it can be achieved by the strong bonding between the metal nanoparticles and the ionomer binder. This presentation investigates the phenomenon of initial performance degradation in AEMWE with an anode catalyst layer composed of metal nanoparticles, highlights the significance of the physical stiffness of the anode catalyst layer, and proposes that the issue can be resolved by introducing a polymer binder with high adhesion between the metal nanoparticles and the ionomer binder.