Two-dimensional high-entropy MWN2 nanosheets for boosted water oxidation in alkaline media†

Abstract

Transition metal nitrides are highly valued owing to their unique properties and diverse applications in coatings, lighting applications, and energy storage. However, the development two-dimensional (2D) metal nitrides presents a significant challenge owing to their strong atomic bonds. Herein, we introduce a family of 2D multicomponent metal nitrides, metal tungsten nitride (MWN₂) nanosheets, via a precursor minimization and nitridation strategy. The composition of M and the stoichiometric ratio can be readily tailored, enabling the successful preparation of high-entropy (FeCoNiMn)WN₂ nanosheets. Prominently, the high-entropy MWN₂ nanosheets demonstrate superior oxygen evolution with an overpotential of only 228 mV at 10 mA cm⁻² and exceptional stability, exhibiting a degradation rate of merely 15 μV h⁻¹ over 1000 hours. Theoretical insights reveal that antisite defects substantially lower the oxygen adsorption energy. This work sheds light on the highly active and stable catalytic properties of 2D metal nitrides for water oxidation.