Mn‐Induced Support Stabilization and Ir Electronic Activation Enable Acid‐Stable, Low‐Loading IrO ₂ Water Oxidation

ABSTRACT The practical application of low‐iridium catalysts for the acidic oxygen evolution reaction (OER) is primarily constrained by the intertwined issues of inadequate activity and stability. Incorporation of Mn into such low‐iridium catalysts is effective, yet the underlying mechanism remains unclear. This study addresses the mechanistic role of Mn doping in enhancing the activity and stability of low‐loading IrO 2 /Co 3 O 4 catalysts. By incorporating Mn 3+ into the octahedral sites of Co 3 O 4 , Mn induces strong Mn─O covalency that reinforces the spinel lattice and stabilizes ultra‐low‐loading IrO 2 nanoparticles, delivering a 51 mV reduction in overpotential and a six‐fold enhancement in operational stability compared to its undoped counterpart at a current density of 10 mA cm −2 . In situ spectroscopic analyses and theoretical calculations decipher the dual role of Mn: it reinforces lattice integrity through strong covalent Mn─O bonds, suppressing ion leaching, while concurrently activating the Ir sites via interfacial Mn─O─Ir electron transfer, which optimizes intermediate adsorption and promotes the efficient oxide‐path mechanism (OPM). This work demonstrates that the targeted dual‐regulation of support chemistry establishes a general principle for designing high‐performance, low‐loading IrO 2 catalysts for acidic OER.