Highly Active IrO x Formation on Strontium Manganite for Acidic Oxygen Evolution

Abstract Iridium‐based oxides are considered the most effective catalysts for the acidic oxygen evolution reaction (OER) due to their superior stability and high activity. However, the high Ir content required poses a significant barrier to their commercial application. Enhancing OER activity and durability while simultaneously reducing the Ir loading remains a significant challenge. Here, porous strontium manganate nanofibers are synthesized via electrospinning and the element leaching behavior is exploited during hydrothermal synthesis to load short‐range ordered IrO x with high activity. In situ characterizations, including X‐ray absorption spectroscopy and Raman spectroscopy, confirm the structural stability of the short‐range ordered IrO x during the OER process. Complementary theoretical calculations, differential electrochemical mass spectrometry, and in situ synchrotron‐radiation infrared spectroscopy reveal that Mn suppresses the lattice oxygen mechanism, enabling the catalyst to stabilize OER through the adsorbate evolution mechanism. The synthesized low‐Ir‐loading catalyst exhibits high OER activity (221 mV overpotential at 10 mA cm −2 ) and robust stability (≈1000 h).