Highly Stable Three‐Dimensional Porous Nickel‐Iron Nitride Nanosheets for Full Water Splitting at High Current Densities

A noble‐metal‐free and highly efficient bifunctional catalyst for overall water splitting is greatly desirable to generate clean and sustainable energy carriers such as hydrogen, but enormous challenges remain. Herein, porous interconnected iron‐nickel nitride nanosheets are designed and grown on carbon fiber cloth (FeNi‐N/CFC); combining a facile electrodeposition method and in situ nitriding process. The as‐synthesized FeNi‐N/CFC, with a low mass loading of 0.25 mg cm −2 , exhibits excellent catalytic activities for both the oxygen evolution reaction (OER) with 20 mA cm −2 at an overpotential ( η ) of 232 mV and also the hydrogen evolution reaction (HER) with 10 mA cm −2 at η= 106 mV. As a bifunctional electrocatalyst for overall water splitting FeNi‐N/CFC only requires a cell voltage of 1.55 V to drive a current density ( j ) of 10 mA cm −2 and shows robust long‐term durability at j >360 mA cm −2 with a negligible change in current density over 60 h; revealing its promising application in commercial electrolyzers.