Oxophilic Sites Activate Asymmetric IrNi Atomic Dimers and Clusters for Efficient Hydrogen Oxidation and CO Tolerance

• • Mass activity of 4.36 A mg−1 Ir at 20 mV, ~23-fold enhancement over Pt/C, directly addresses the high cost of Pt by reducing Ir loading while maintaining performance. • • 5-fold longer stability than Pt/C in HOR, indicating improved durability for long-term PEMFC operation, reducing replacement frequency and cost. • • Rated power density of 1.18 W cm−2 in PEMFC anode, demonstrating practical viability for high-power applications, surpassing typical Pt/C anodes. • • Superior CO tolerance over monometallic Ir and Pt/C in half-cell and full-cell, enabling operation with lower-purity hydrogen and reducing system complexity.