Interface Engineering Between Membrane and Electrodeposited-IrO₂ Electrode Using One-Sided Hot Pressing to Produce Efficient Proton Exchange Membrane Water Electrolyzers

Designing the structure of a membrane electrolyte assembly (MEA) is essential to maximizing catalyst utilization and improving the electrode performance at the single-cell level. In this study, one-sided hot pressing was employed to enhance catalyst utilization in an electrodeposited IrO₂ electrode for use in proton exchange membrane water electrolyzer (PEMWE) systems. An oxygen electrode loaded with 0.13 mg_Ir cm⁻² IrO₂ was prepared via the anodic electrodeposition onto a Ti porous transport layer (PTL), which was subsequently assembled with a Nafion membrane via one-sided hot pressing. The IrO₂/Ti-PTL electrode penetrated the membrane, and its pores were partially filled with the membrane component. The mean vertical thickness of the zone in which the IrO₂/Ti-PTL pores are filled with the membrane strongly affected the contact area between the electrode and electrolyte, with greater thickness resulting in a broader electrode/electrolyte interface but reduced reactant (H₂O) accessibility. The cell current density at 1.7 V and 80 °C was significantly improved to 1.44 A cm⁻² using the one-sided hot pressing approach; these were comparable to the values reported for state-of-the-art particle-type electrodes bearing higher loadings of platinum group metal (PGM) catalysts (~ 0.5 mg). This work highlights the great potential of film-type electrodes for use as low-PGM oxygen electrodes in PEMWEs.