Anode Catalyst Layers for AEM-WE: Implementation, Characterisation and Evaluation of Different Synthesis Routes

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The global energy sector's transformation and requisite technological shifts present an unprecedented challenge for politics, industry, and research. Green hydrogen, produced through water electrolysis, is pivotal for storing fluctuating renewable electricity and decarbonizing power demanding industries (e.g. steel production). Current electrolysis technologies do not achieve high efficiencies or require critical materials such as iridium, titanium or flourinated polymers. For these reasons, alkaline electrolyte membrane water electrolysis (AEM-WE) has garnered increased attention from industry and research in recent years. The technology involves many construction principles and advantages of the PEM-WE without its disadvantages. However, further research is necessary to understand electrochemical interactions and technical implementation, especially in catalyst-related topics.In this work, therefore different types of catalyst layers are prepared and characterized. Depending on the catalyst type distinct preparation methods are applied and the resulting layers are evaluated electrochemically. Full cell experiments are conducted with combined membrane electrode assemblies and in conjunction with electrochemical impedance spectroscopy are used to provide information on contact resistance, electrochemical surface area and overall mass activity.The applied catalytic materials are made by galvanic deposition, corrosion, precipitation and physical vapour deposition of active species on support materials. Based on the employed preparation method the catalyst implementation and subsequent utilization varies. In particular catalysts from precipitation and PVD-coating were studied in terms of deposition configurations, catalyst loading and a comparison to more widespread catalyst systems. Due to the increase of the specific active surface area by the shape of the synthesised core-shell-like particles, even small amounts of active species could be implemented in highly active layers and thus enable high current densities in optimised electrolysers. Figure 1