Tailoring high-performance catalyst architectures via ‘accessional ionomer coatings’ for anion exchange membrane water electrolysis

Anion exchange membrane water electrolysis (AEMWE) represents a viable solution for achieving large-scale, low-cost hydrogen production. The catalyst and ionomer layers play a crucial role in facilitating the electrochemical reactions on the electrodes in AEMWE. However, the optimization of catalyst-ionomer configurations through architectural and structural development remains an understudied area of research, despite its critical importance. Here, this study involved the preparation and investigation of multiple catalyst-ionomer configurations, including those with single and dual ionomer layers at both the cathode and anode. Our findings indicate that incorporating an additional ionomer layer in the catalyst-coated membrane-based membrane electrode assemblies (MEAs) improve their performance by enhancing interfacial contact area and facilitating charge transfer, compared to MEA configurations without ionomer layers. While ionomer-modified catalyst-coated substrate-based MEA configurations do not show a significant improvement in activity, they demonstrate lower potentials during a 150-h stability test. Furthermore, cost-effective MEAs are fabricated by replacing noble metal anode catalysts with commercially available NiFe nanoparticles, which exhibit comparable catalytic activity and enhanced durability.