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

Abstract 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 2 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 support bonding and optimizes *OOH adsorption energetics, thereby enabling concurrent activity‐stability improvements. The resultant Ir@IrO x /m‐Nb‐TiO 2 anode achieves exceptional PEMWE performance with ultralow loading (0.27 mg Ir cm −2 ), requiring a low electrolysis voltage of 1.72 V to reach industrial current densities of 2 A cm −2 , 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.