Comprehensive 3d Transition Metal Single‐Atom Modulation Tunes Ni‐MOF D‐Band for Alkaline OER

Efficient alkaline water electrolysis is often hindered by the slow kinetics of the oxygen evolution reaction (OER). Here, Ni‐MOFs grown on nickel foam, doped with trace amounts of first‐row transition‐metal single atoms (M = V–Zn), are designed to systematically investigate their effects on catalytic activity. Among all dopants, atomically dispersed Fe (0.24 wt.%) most effectively shifts the Ni d‐band center toward the Fermi level, significantly lowering the * OH → * O energy barrier from 1.93 to 1.64 eV. The optimized Ni‐MOF/NF‐Fe electrode achieves an overpotential of 246 mV at 100 mA cm − 2 and maintains outstanding stability with only 9 mV potential drift over 10 h. Notably, in an 80 °C anion‐exchange‐membrane electrolyzer, a Ni‐MOF/NF‐Fe||Pt/C couple delivers 0.50 A cm −2 at just 1.56 V—160 mV lower than the RuO 2 benchmark—and operates stably for 580 h. X‐ray absorption fine structure (XAFS) confirm Fe‐O‐Ni motifs as the origin of the enhanced performance, demonstrating the power of trace‐level Fe doping for scalable, noble‐metal‐free OER catalysts.