Defect‐Rich Ni3FeN Nanocrystals Anchored on N‐Doped Graphene for Enhanced Electrocatalytic Oxygen Evolution

Abstract Owing to their unique optical, electronic, and catalytic properties, metal nitrides nanostructures are widely used in optoelectronics, clean energy, and catalysis fields. Despite great progress has been achieved, synthesis of defect‐rich (DR) bimetallic nitride nanocrystals or related nanohybrids remains a challenge, and their electrocatalytic application for oxygen evolution reaction (OER) has not been fully studied. Herein, the DR‐Ni 3 FeN nanocrystals and N‐doped graphene (N‐G) nanohybrids (DR‐Ni 3 FeN/N‐G) are fabricated through temperature‐programmed annealing and nitridation treatment of NiFe‐layered double hydroxides/graphene oxide precursors by controlling annealing atmosphere. In the nanohybrids, the DR‐Ni 3 FeN nanocrystals are anchored on N‐G, and mainly show twin crystal defects besides ≈10% of stacking faults. Such nanohybrids can efficiently catalyze OER in alkaline media with a small overpotential (0.25 V) to attain the current density of 10 mA cm −2 and a high turnover frequency (0.46 s −1 ), superior to their counterparts (the nearly defect‐free Ni 3 FeN/N‐G), commercial IrO 2 , and the‐state‐of‐art reported OER catalysts. Except for the superior activity, they show better durability than their counterparts yet. As revealed by microstructural, spectroscopic, and electrochemical analyses, the enhanced OER performance of DR‐Ni 3 FeN/N‐G nanohybrids originates from the abundant twin crystal defects in Ni 3 FeN active phase and the strong interplay between DR‐Ni 3 FeN and N‐G.