Electronic Structure Regulation by Fe Doped Ni‐Phosphides for Long‐term Overall Water Splitting at Large Current Density

Abstract Acquiring a highly efficient electrocatalyst capable of sustaining prolonged operation under high current density is of paramount importance for the process of electrocatalytic water splitting. Herein, Fe‐doped phosphide (Fe‐Ni5P4) derived from the NiFc metal−organic framework (NiFc‐MOF) (Fc: 1,1′‐ferrocene dicarboxylate) shows high catalytic activity for overall water splitting (OWS). Fe‐Ni5P4||Fe‐Ni5P4 exhibits a low voltage of 1.72 V for OWS at 0.5 A cm−2 and permits stable operation for 2700 h in 1.0 m KOH. Remarkably, Fe‐Ni5P4||Fe‐Ni5P4 can sustain robust water splitting at an extra‐large current density of 1 A cm−2 for 1170 h even in alkaline seawater. Theoretical calculations confirm that Fe doping simultaneously reduces the reaction barriers of coupling and desorption (O*→OOH*, OOH*→O2 *) in the oxygen evolution reaction (OER) and regulates the adsorption strength of the intermediates (H2O*, H*) in the hydrogen evolution reaction (HER), enabling Fe‐Ni5P4 to possess excellent dual functional activity. This study offers a valuable reference for the advancement of highly durable electrocatalysts through the regulation derived from coordination frameworks, with significant implications for industrial applications and energy conversion technologies.