High-performance electrolytic oxygen evolution with a seamless armor core–shell FeCoNi oxynitride

Abstract

Highly active, low-cost, and durable electrocatalysts for the water oxidation reaction are pivotal in energy conversion and storage schemes. Here we report a nitride-core, oxide-shell-armor structured FeCoNi oxynitride as an efficient oxygen evolution electrocatalyst with a homogeneous nitride (Fe_0.70Co_0.56Ni_0.92N_1.0O_0.06) core and an oxide (Fe_0.48Co_0.1Ni_0.21N_0.05O_1.0) shell. The catalyst demonstrated excellent activity for the oxygen evolution reaction with a current density of 10 mA cm⁻² at a low overpotential of 0.291 V in alkaline media (1 M KOH), which is superior to the activities of commercial IrO₂, RuO₂, and Pt/C catalysts and comparable to those of state-of-the-art catalysts (e.g., NiFe-LDH, NiCo₂O₄, O-NiCoFe-LDH). Density functional theory simulations suggested that the incorporation of multiple metal elements can indeed improve the reaction energetics with a synergistic effect from the core–shell structure. This unique structure of a nitride-core with a oxide-shell presents a new form of multimetallic oxynitride with compelling performance in electrolytic oxygen evolution.