Inter‐Doping ZrO ₂ ‐5.5RuO ₂ Heterostructures for Enhanced Efficiency and Stability in Acidic Oxygen Evolution

ABSTRACT Acid water electrolysis represents a crucial technology for the sustainable production of hydrogen. However, acidic media and high oxidation potential can lead to oxidative dissolution of catalysts (e.g., RuO 2 → soluble RuO 4 ), resulting in a rapid loss of active sites. Here, we present an inter‐doping strategy for the construction of zirconium‐ruthenium oxide heterostructure (ZrO 2 ‐xRuO 2 ) through metal–organic framework confined effect and fused salt mixing method. Specifically, ZrO 2 ‐5.5RuO 2 achieves an ultralow overpotential of 137 mV at 10 mA cm −2 , setting a new benchmark for oxygen evolution catalysts under acidic conditions. Its mass activity (337.5 A g Ru −1 ) at 250 mV overpotential is 32.3 times that of commercial RuO 2 . The catalyst also demonstrates long‐term stability for 655 h, far superior to commercial RuO 2 (<6 h). The remarkable activity and stability can be attributed to the Zr─O─Ru interfacial junction, resulting in low‐valence Ru sites and high‐valence Zr sites. The charge redistribution optimizes the adsorption energy of reactive oxygen species and minimizes the involvement of lattice oxygen, thus leading to a significant enhancement in both activity and stability. This work provides a novel insight for addressing the activity‐stability dilemma through atomic‐level interface engineering, establishing a new paradigm for the large‐scale application of green hydrogen energy.