Ordered Mesoporous Cobalt–Nickel Nitride Prepared by Nanocasting for Oxygen Evolution Reaction Electrocatalysis

Abstract Transition metal nitrides are of considerable interest for energy conversion and storage applications. Given this, synthesis of nanostructured 3D transition metal nitrides is of contemporary interest. Here, a hard templating simple and efficient pathway to synthesize 3D ordered‐mesoporous ternary nitrides NiCo 2 N is reported using the mesoporous silica KIT‐6 hard template. Benefitting from its large surface area and accessible pores, uniform shape, and enhanced infiltration capacity for electrolyte, mesoporous NiCo 2 N demonstrates superior electrode performance for oxygen evolution reaction (OER) in alkaline medium. As‐synthesized mesoporous ternary nitride NiCo 2 N shows desirable performance with very low overpotential (289 mV), and yields ≈10 mA cm −2 geometric current density. This is lower than the values of IrO 2 and that of mesoporous binary nitrides CoN and Ni 3 N electrocatalysts. NiCo 2 N shows a small Tafel slope and smallest semicircle. Moreover, as‐synthesized NiCo 2 N exhibits low loss of activity after 10 h test for OER in alkaline solution. This work explores a promising way to produce OER electrocatalyst Co–Ni‐based ternary nitrides for water splitting applications.