Characterization of Transport Pathways in Electrolyzers Using Neutron and X-Ray Tomography

Abstract

Electrolysis is a critical component to realizing a true green hydrogen economy. The performance and efficiency of an electrolyzer is directly tied to the multiphase transport that occurs within the porous transport layer (PTL). The PTLs must allow sufficient water transport to the catalyst layer to maintain the reaction while removing the product gases. PTLs are typically created from titanium foams or sintered from titanium powders or fibers. The resultant structure is heterogenous and requires 3D imaging to properly capture the pore structure and transport pathways. The use of titanium for the PTL can make it difficult to track the multiphase flow using X-rays alone as the X-ray energy required to penetrate 1 cm or more reduces the contrast between water and oxygen without the use of contrast agents that could affect the reaction. Neutrons provide a penetrating probe capable of imaging through titanium while having extreme sensitivity to water. Combing neutrons and high energy X-rays provides an easy way to identify all components in the PTL, i.e., the solid structure, oxygen, and water. The National Institute of Standards and Technology provides the Neutron Imaging Facility to the larger research community through the Center for Neutron Research facility user program. This instrument provides the ability to perform simultaneous neutron and X-ray tomography. Moving from 2D radiography to 3D tomography is critical to fully understand the influence of the PTL pore structure on the multiphase transport. This talk will give an overview of the instrument capabilities, showcase past success for neutron imaging of electrolyzers, and provide current progress on development of hardware and data reduction methods for simultaneous neutron and X-ray tomography of electrolyzers.