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‐Ni 5 P 4 ) derived from the NiFc metal−organic framework (NiFc‐MOF) (Fc: 1,1′‐ferrocene dicarboxylate) shows high catalytic activity for overall water splitting (OWS). Fe‐Ni 5 P 4 ||Fe‐Ni 5 P 4 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‐Ni 5 P 4 ||Fe‐Ni 5 P 4 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 * →O 2 * ) in the oxygen evolution reaction (OER) and regulates the adsorption strength of the intermediates (H 2 O * , H * ) in the hydrogen evolution reaction (HER), enabling Fe‐Ni 5 P 4 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.