Amorphous IrO_x nanoparticles on N-doped carbon matrix islands for enhancing proton exchange membrane water electrolysis

The development of an electrocatalyst and electrode that maintain their integrity under a high current density is vital for the advancement of PEMWE. In this context, we develop amorphous iridium oxide (IrO_x) anchored on an N-doped carbon matrix island, directly formed on titanium porous transport layer through a simple method consisting of spray coating and pyrolysis. Remarkably, this configuration achieves 10 mA/cm² current density for oxygen evolution reaction (OER) in acidic electrolyte, with only a 240 mV overpotential required, and the durability of this structure is confirmed by long-term and accelerated stress tests. These merits enable the unit cell to achieve over 6 A/cm² at 2 V cell voltage without considerable degradation. This catalyst fulfills the requirement of the US Department of Energy's 2026 target in performance (> 3 A/cm² at 1.8 V) and in energy efficiency (> 65 %), as well as in the electricity cost for H₂ production (US $2.0/kg H₂).