Vertically Arrayed Co4N/MoN Nanosheets for Robust Alkaline Electrocatalytic Hydrogen Evolution at Ampere-Level Current Density

Abstract

Metal nitride electrocatalysts have been extensively developed for efficient alkaline water splitting, but it still remains a huge challenge in improving their stability especially at high current density of over 500 mA cm⁻². Herein the Co₄N/MoN electrocatalyst with hierarchical nanoparticle-assembled nanosheet arrays is fabricated by a facile electrodeposition-nitridation method for alkaline hydrogen evolution reaction (HER). Results show that it exhibits an impressively low overpotential of 238 mV and high durability at 1.0 A cm⁻² for over 100 h, which is the best among the reported cobalt-based nitride electrocatalysts with both excellent HER activity and robust stability at ampere-level current density. The superior intrinsic HER activity is mainly ascribed to the synergistic effect of Co₄N and MoN, which can effectively reduce the H₂O dissociation energy barrier and accelerate the alkaline HER kinetics. Moreover, benefiting from the vertically arrayed nanosheet structure with a solid framework and excellent mechanical strength, robust water electrolysis even at ampere-level current density can be achieved. This work provides an alternative way to develop metal nitride electrocatalysts via fabricating hierarchical heterostructure for efficient and stable industrial water splitting.