Synchrotron-based μ-CT was performed at Diamond Light Source on the I13-2 imaging beamline. A pink X-ray beam generated from an insertion device with weighted mean energy of 27 keV was used along with a PCO Edge 5.5 visible light detector set up with a 2× objective lens. This configuration allowed for a pixel size of 1.625 µm over a 4.2 mm by 3.5 mm field of view, capturing the entire active volume of the electrolyser. Acquisition of a single tomography required 4 min and 3 s of exposure. Tomography reconstructions were performed with SAVU software, a python based reconstruction framework , using the FBP reconstruction algorithm. The data was first corrected for the background and lens distortions before feeding to the reconstruction algorithm.