Investigating Material Transformations in Water Electrolysis for Green Hydrogen Generation

Sammanfattning

Water electrolysis for Green Hydrogen production is an integral technology that is necessary in achieving climate neutrality. With different technological solutions been proposed, proton exchange membrane water electrolysis (PEMWE) is one of the highly investigated technologies, as it has higher efficiency, higher hydrogen purity and being compatible with renewable energy. However, one of the key issues with PEM water electrolysis is the inflated cost of iridium, which is the catalyst for the oxygen evolution reaction (OER). Recently, the Swedish company, Smoltek Hydrogen (SH) has made major strides in reducing the amount of Iridium needed for PEMWE, by creating a novel porous transport elctrode (PTE) for the OER. This report investigates the material transformation on this developed by SH layer, where the catalyst layer consists of metallic Ir particles, which is deposited over nanofibers ofcarbon (CNF) with a platinum thin anti corrosion layer coverage. In this report, we try to investigate the material transformation on the electrode surface using x-ray photoelectronspectroscopy (XPS) and scanning electron microscopy (SEM) techniques. Two samples were taken for the study: a pristine sample and another sample which had undergone a 5000-cycle accelerated durability test in acid electrolyte. The results from this investigation indicate anoxidation of Ir(0) to predominantly Ir(IV) with contribution from other oxidation state(s) in the long ran sample. The formation of Ir(IV) is in line with the OER results and also from other studies. This also suggests that it would be more efficient to apply Ir in its favourableoxidated state (IrOx) when assembling the porous transport electrode (PTE) in the electrolyzer.