Heterointerface Anchored Ir with Localized Strong Orbital Coupling for Durable Proton Exchange Membrane Water Electrolysis.

The imperative to minimize iridium usage in proton exchange membrane water electrolysis (PEMWE) process presents a pivotal challenge for hydrogen economy deployment, while inherent destabilization of iridium (Ir) active sites under corrosive operational conditions, originating from insufficient Ir bonding strength, remains a fundamental barrier. Here, we resolve this dilemma through heterointerface-engineered stabilization, where the strategically constructed Nb-TiO rutile/anatase heterophase homojunction stabilizes Ir sites with enhanced orbital overlap and intensified charge transfer. This atomic-scale anchoring mechanism, validated by operando characterization and theoretical calculations, strengthens Ir─O bonding and optimizes *OOH adsorption energetics, thereby enabling concurrent activity-stability improvements. The resultant Ir@IrO/m-Nb-TiO anode achieves exceptional PEMWE performance with ultralow loading (0.27 mg cm), requiring a low electrolysis voltage of 1.72 V to reach industrial current densities of 2 A cm, coupled with unprecedented durability with <1.7% voltage decay over 3000 h. This interface design philosophy establishes a general paradigm for developing active and stable supported electrocatalysts for PEMWE and beyond.