Advancements in ordered membrane electrode assembly (MEA) for water electrolysis

Proton exchange membrane (PEM) and anion exchange membrane (AEM) water electrolyzers exhibit superior efficiency and produce higher purity hydrogen compared to traditional alkaline water electrolyzers due to their membrane electrode assembly (MEA) design. However, random structures presented in current MEA designs introduce significant transport resistance for electrons and mass (ion, gas and liquid), consequently degrading the overall performance of electrolyzes. In contrast, ordered MEA structures are characterized by well-defined arrangements of pores, channels or pathways within catalyst layers (CLs), porous transport layers (PTLs), and ion exchange membranes (IEMs). These ordered configurations facilitate efficient highways for the transfer of electrons and mass. Recent diverse ordered MEA designs have demonstrated significant improvements in overall electrochemical efficiency in both PEM and AEM water electrolyzers. In this review, we will examine recent advancements in ordered MEA designs for water electrolyzers focusing on innovations in fabrication methods and interface morphologies, as well as their electrolysis performance. This review may provide comprehensive guidelines for designing ordered MEAs for both PEM and AEM electrolyzers. © 2024 Elsevier B.V.