Visual identification of the electrochemically active region in anode catalyst layer of PEMWE

Abstract

To commercialize the polymer electrolyte membrane water electrolysis (PEMWE), it is necessary to reduce the amount of expensive novel metal catalysts. Thus, a study on the utilization of the catalyst layer (CL) is required. Currently, the utilization of the CL was described only as of the location where bubbles are generated, and bubbles were generated only at the interface between the porous transport layer (PTL) and the CL. However, this method is different from the actual system and cannot explain that the non-PTL-contact part is not used completely or is used less. Therefore, in this study, the area in which the actual reaction can occur was visualized by reducing the iridium oxide by an electrochemical method. After reducing the CL using the cyclic voltammetry (CV) method, it was confirmed that the non-PTL-contact part is partially reduced through energy dispersive X-ray spectroscopy (EDS) elemental analysis, and the utilization of the CL was different depending on the catalyst loading and the location of the rib and channel confirmed. Also, by observing the change of the CL in a humidified environment, it was shown that cracks that did not appear in the dried state appeared in the CL in a humidified environment. For this reason, it was difficult to use the non-PTL-contact part in an actual cell driving condition.