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-NiP) derived from the NiFc metal-organic framework (NiFc-MOF) (Fc: 1,1'-ferrocene dicarboxylate) shows high catalytic activity for overall water splitting (OWS). Fe-NiP||Fe-NiP exhibits a low voltage of 1.72 V for OWS at 0.5 A cm and permits stable operation for 2700 h in 1.0 m KOH. Remarkably, Fe-NiP||Fe-NiP can sustain robust water splitting at an extra-large current density of 1 A cm 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 ) in the oxygen evolution reaction (OER) and regulates the adsorption strength of the intermediates (HO, H) in the hydrogen evolution reaction (HER), enabling Fe-NiP 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.