Electronic modulation of MOF-derived IrCoFe@C and over-boiling strategy for enhanced bifunctional alkaline water...

Bifunctional electrocatalysts with reduced noble-metal utilization are essential for achieving a low carbon footprint in advanced hydrogen production through water electrolysis. However, high energy barriers, sluggish mass/charge transfer, and insufficient stability of transition-metal systems limits their applications. Herein, we propose Ir-modified CoFe heterostructure (Ir_0.01Co_0.1Fe@C) for elevated-temperature alkaline water electrolysis to boost mass/charge transfer and reduce energy barriers. Incorporation of Ir and Co into the FeC framework establishes strong interfacial electronic coupling, modulating the d-band center, optimizing the adsorption energetics of key intermediates, and significantly accelerating intrinsic HER/OER kinetics. DFT calculations further reveal near-optimal hydrogen adsorption at the Co site (ΔG_H^⁎ = -0.35 eV) together with the lowest calculated *OOH formation barrier. Benefitting from the tailored electronic structure, enhanced kinetics and mass transport at elevated temperature, Ir_0.01Co_0.1Fe@C exhibits outstanding bifunctional performance, delivering ultralow overpotential of 12 mV for HER and 98 mV for OER at 10 mA cm^-2 at over-boiling of 120 °C, demonstrating strong elevated-temperature HER/OER performance. Besides, the new catalyst-assembled electrolyzer requires only 1.425 V at 10 mA cm^-2 with 120 h stability at 25 °C and 60 min short-term operation at 120 °C, offering a promising blueprint for next-generation high-performance bifunctional electrocatalysts.