Controlled Structural Activation of Iridium Single Atom Catalyst for High-Performance Proton Exchange Membrane Water Electrolysis

Iridium single atom catalysts are promising oxygen evolution reaction (OER) electrocatalysts for proton exchange membrane water electrolysis (PEMWE), as they can reduce the reliance on costly Ir in the OER catalysts. However, their practical application is hindered by their limited stability during PEMWE operation. Herein, we report on the activation of Ir-doped CoMn₂O₄ in acidic electrolyte that leads to enhanced activity and stability in acidic OER for long-term PEMWE operation. In-depth material characterization combined with electrochemical analysis and theoretical calculations reveal that activating Ir-doped CoMn₂O₄ induces controlled restructuring of Ir single atoms to IrO_x nanoclusters, resulting in an optimized Ir configuration with outstanding mass activity of 3562 A g_Ir^–1 at 1.53 V (vs RHE) and enhanced OER stability. The PEMWE using activated Ir-doped CoMn₂O₄ exhibited a stable operation for >1000 h at 250 mA cm^–2 with a low degradation rate of 0.013 mV h^–1, demonstrating its practical applicability. Furthermore, it remained stable for more than 400 h at a high current density of 1000 mA cm^–2, demonstrating long-term durability under practical operation conditions.