Effect of perfluorosulfonic acid ionomer in anode catalyst layer on proton exchange membrane water electrolyzer performance

The equivalent weight (EW) and side-chain length of perfluorosulfonic acid (PFSA) ionomers have been found to significantly influence the performance of different proton exchange membrane (PEM)-based electrochemical devices. However, few reports have investigated their influence on PEM water electrolyzers (PEMWE). In this study, we investigate the influence of EW and side-chain length on PEMWE's membrane electrode assemblies (MEAs) which are fabricated by four different PFSA ionomers. It is found that the change in PFSA ionomer EWs barely influences the microstructure of the anode catalyst layer (ACL) but affects its surface wettability and MEA performance. Different from that in PEM fuel cells, MEA in PEMWEs prepared by PFSA ionomers with higher EWs shows better cell performance. The voltage difference comes from the change in the mass transport overpotential which is up to 113 mV with the comparison between PFSA ionomers with the highest EW and the lowest EW, which attributes to the changed wettability and water-oxygen transport of the ACLs. The influence of

Automated summary

The study investigates the influence of equivalent weight (EW) and side-chain length of perfluorosulfonic acid (PFSA) ionomers on the membrane electrode assemblies (MEAs) of proton exchange membrane water electrolyzers (PEMWEs). It is found that the change in PFSA ionomer EWs affects the surface wettability and MEA performance, resulting in a voltage difference due to changed mass transport overpotential.