Engineering Conductive Ti₄O₇ Networks for Efficient and Durable Low-Ir-Loading Anode in Proton Exchange Membrane...

Reducing iridium (Ir) loading in the anode catalyst layer (ACL) of proton exchange membrane water electrolysis (PEMWE) remains a key challenge for scaling up green hydrogen production. However, low-Ir-loading often results in poor electrical/protonic connectivity and mechanical integrity, causing limited performance and durability. Herein, an ionomer targeting strategy (ITS) is proposed to minimize the insulating perfluorosulfonic acid ionomer coverage on conductive Ti₄O₇ additives while guiding the ionomer selectively wrapping onto IrO₂ catalyst. This approach increases the in-plane electrical conductivity by 63.8% and reduces the proton transport resistance by 81.0% versus the conventional ACL. The PEM electrolyzer with optimized ACL achieves a platinum group metal (PGM) utilization of 0.072 g_PGM kW^-1 at a PGM loading of 0.3 mg cm^-2 (both electrodes combined), outperforming the U.S. Department of Energy 2026 technical target of 0.1 g_PGM kW^-1. This represents the first report of achieving this benchmark for PEMWE. Crucially, the ACL exhibits a voltage decay rate of 75 µV h^-1 at 1.5 A cm^-2 for 1600 h, ≈20-fold lower than the conventional ACL. The ITS enables a selective ionomer wrapping mechanism in the ACLs, providing a practical and scalable pathway to an efficient, durable, and low-Ir-loading PEMWE system.