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

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.