Fabrication of Bipolar Membrane Electrolyzers for Seawater Electrolysis: Proof-of-Concept, Operando Design, and Fundamental Studies

Hydrogen (H 2 ) is a critical industrial feedstock, essential in the production of fertilizer, steel, and fuels. Its demand is anticipated to increase ten-fold by 2050 due to its pivotal role in various new green technologies. Renewable energy-driven bipolar membrane water electrolyzers (BPMWEs) are a promising technology for sustainable production of H 2 from seawater and other impure water sources. Here we present a detailed protocol on the assembly and operation of zero-gap membrane electrode assembly (MEA) BPMWE with water dissociation layers 1 . We describe steps for spray coating both electrodes and membranes, electrolyzer assembly, and electrochemical evaluation. This protocol provides an avenue to highlight key considerations in BPMWE fabrication methodology to ensure comparable data and rapid progress. We further highlight how this BPM platform can be used for a variety of scientific applications ranging from the seawater resistant BPMWE to an operando water electrolyzers to examine catalyst dynamics through X-ray absorption spectroscopy (XAS). As we work together towards a cleaner future, the detailed BPMWE protocol enables scientific communication, aiding in reproducible electrolyzer assembly practices, and accelerating the optimization of next-generation BPM-based devices.