Nickel-Rich Ni₃N Particles Stimulated by Defective Graphitic Carbon Nitrides for the Effective Oxygen Evolution Reaction

The development of an effective and inexpensive electrocatalyst for the oxygen evolution reaction (OER) is the key to achieve high hydrogen production since water splitting has sluggish OER kinetics. Herein, a composite of nickel-rich nickel nitride (NR-Ni₃N) with graphitic carbon nitrides (GCNs) was prepared for the electrocatalytic OER, showing a low overpotential of ∼290 mV, a small Tafel slope of ∼70 mV dec^–1 at 10 mA cm^–2 current density, and low loss of activity after 36 h of test in an alkaline electrolyte, outperforming the pure Ni₃N and even the noble catalyst RuO₂. The characterization results revealed that the defective GCNs can promote the generation of a Ni-rich region in Ni₃N in the nitridation process, and the high conductivity of the formed robust Ni–Ni₃N heterojunction and its strong synergistic effect with GCNs explain the excellent OER electrocatalytic performances of NR-Ni₃N/GCNs. This work provides a novel feasible strategy for the development of highly active OER electrocatalysts.