Vertical kinetically oriented MoS₂-Mo₂N heterostructures on carbon cloth: a highly efficient hydrogen evolution electrocatalyst

Rationally designed nanostructures can synergistically provide more active sites to optimize the electrocatalytic properties and decrease the energy barrier of the hydrogen evolution reaction (HER). Although MoS₂ is a promising two dimensional (2D) electrocatalyst, the curved nanoplates adversely affect the delivery of H₂ during the HER. Herein, kinetically oriented MoS₂ nanoflakes are prepared vertically on Mo₂N nanoneedles anchored on flexible carbon cloth (MoS₂-Mo₂N/CC). The three-dimensional (3D) skeleton composed of carbon cloth (CC) and Mo₂N prevents collapse of MoS₂ during fabrication and electrochemical reactions. Moreover, the strong electronic interactions between MoS₂ and Mo₂N enhance charge transfer, moderate the hydrogen binding energy, and decrease the reaction energy thermodynamically. MoS₂-Mo₂N/CC delivers moderate hydrogen binding energy and fast H₂desorption further enhancing the HER activity. Owing to the optimized hybrid structure, MoS₂-Mo₂N/CC exhibits a small overpotential of 121 mV at 10 mA cm^-2, small Tafel slope of 49.6 mV dec^-1, and outstanding stability of 97.4% at 50 mA cm^-2. The results reveal the large potential of vertically oriented HER catalysts in energy storage and conversion.