Complementary X-ray and neutron imaging of water electrolysers for green hydrogen production

With the growing interest in green hydrogen as an energy vector, advances in all types of electrolysers are urgently needed. Imaging methods utilising X-rays and neutrons are seen as highly complementary techniques for visualising, analysing and quantifying the properties of electrolysers, whose materials and operational processes span multiple length and timescales. In this perspective, we first outline four key challenge areas for all electrolyser technologies: using less, using alternative materials, increasing durability and recycling, and introduce the various materials (and their corresponding feature sizes and relevant imaging methods) found in the components of the four main electrolyser types anion exchange membrane (AEM), polymer electrolyte membrane (PEM), alkaline water electrolyser (AWE) and solid oxide electrolyser cell (SOEC). After introducing key relevant concepts for X-ray and neutron imaging, we present a detailed summary of the use of these techniques for the imaging of electrolyser technologies. As highlighted throughout the review, these two methods, when used in a complementary manner, are able to capture the full breadth of complex, multiscale, multiphase materials and dynamics that occur in electrolyser technologies. Finally, we give our perspective on the areas we foresee as being highly important for future complementary, multiscale studies of electrolyser materials. By harnessing the power of both imaging methods together, we can ensure the accelerated discovery and optimisation of the next generation of electrolyser technologies, ensuring a stable and reliable supply of green hydrogen in the coming decades and beyond.