Holey Sheets of Interconnected Carbon-Coated Nickel Nitride Nanoparticles as Highly Active and Durable Oxygen Evolution Electrocatalysts

The accessible oxide surface with a defect is of fundamental importance for oxygen evolution electrocatalyst design. Here, a stable and ultrathin nickel oxide defect layer with Ni-N is formed in situ and confined at the interface between Ni3N and covered carbon. Holey sheets of ultrathin carbon-coated nickel nitride (Ni3N) were successfully prepared via a facile polymerization and in situ nitridation strategy and exhibit outstanding oxygen evolution reaction (OER) performance as well as high long-term durability in alkaline electrolyte. The optimized composite possesses a porous and hollow nanostructure, metallic properties, and a superior activity with a low overpotential (∼260 mV at a current density of 10 mA cm-2), small Tafel slope (∼51 mV dec-1), and low loss of activity after a 10 h test in alkaline electrolyte. The significant OER activity and stability are mainly ascribed to (I) ultrathin oxide layers as active sites confined between the Ni3N core and outside carbon coating, (II) overoxidation of Ni3N suppressed by carbon coating synthesized in situ to improve the stability for OER, and (III) strong coupling of Ni3N particles with an ultrathin carbon coating derived from in situ nitridation to efficiently promote fast electron transfer. This catalyst design strategy will greatly aid in the development of highly active OER electrocatalysts in the near future.