(358e) Tracking Material Dynamics in Zero-Gap Water Electrolyzers Under Operando Conditions

Water electrolyzers are a promising technology to electrify H₂ production. While conventional alkaline electrolysis is the most mature technology, limited capability for dynamic high current density operation necessitates a different approach. Zero-gap water electrolyzers use a solid polymer-based electrolyte membrane which enables dynamic high current density operation essential for producing high pressure and high purity H₂ from renewable energy. While promising, these electrolyzers are challenged by significant cost and durability issues that require further research and development to meet DOE cost targets of $1 per kg within the next decade.

The membrane electrode assembly (MEA) where water is converted into H₂ and O₂ is the heart of a zero-gap electrolyzer. The complex interactions between water, gas, ionomer, catalyst, and porous transport layer have a profound impact on electrochemical performance and understanding the dynamic changes to these interfaces during device operation is challenging. Here, we present a range of hardware and techniques we have developed to probe MEA dynamics under operando conditions (>2 A cm^-2). These include synchrotron compatible electrolyzer hardware that enables techniques such as HERFD-XANES to track the evolution of catalyst oxidation states, as well as x-ray radiography to track bubble transport. Furthermore, we have also developed lab-based methods such as online ICP-MS which enable us to track degradation resulting from material loss. Together, these methods enable insight into the dynamic chemical processes and degradation mechanisms that dictate device performance and inform design of durable next-generation water electrolyzers.