Accelerating water dissociation at hierarchical nanostructured electrocatalyst for efficient hydrogen evolution

The sluggish kinetics of the water electrolysis reaction is a key issue for hydrogen production, so the rational design of a high-efficiency hydrogen evolution reaction (HER) electrocatalyst with various structures has attracted extensive attention. Herein, a coaxial hierarchical three-dimensional (3D) nanostructure, Pt@Mo–S–Ni-CNTs, was prepared. In this nanostructure, carbon nanotubes (CNTs) as the core, Mo–S–Ni ultrathin nanosheets as shells, and ultrasmall metal nanoparticles (NPs) were grown uniformly on the surface of Mo–S–Ni nanosheets (NSs). At a current density of 10 mA cm−2, the catalyst under investigation has remarkable hydrogen evolution reaction (HER) activity under acidic conditions. The overpotential (η10) is measured to be 61.2 mV, while the Tafel slope is determined to be 40.2 mV dec−1. Meanwhile, in an alkaline medium, η10 is 80.5 mV and the Tafel slope is 52.3 mV dec−1. It also shows great mass activities of 1.32 A mg−1 and 1.86 A mg−1, which are higher than those of commercial Pt/C HER catalysts. Impressively, the excellent HER activity and durability of Pt@Mo–S–Ni-CNTs are mainly attributed to the close binding effects among Pt, MoS2, and NiS. Theoretical simulations show that the MoS2/NiS interfaces facilitate H2O dissociation and that Platinum (Pt) enhances the absorption of hydrogen atoms (H) and increases the charge transfer kinetics of the Mo–S–Ni, thus significantly improving the HER activity. This work highlights the importance of engineering interface nanosheets based on transition-metal dichalcogenides for enhanced HER performance.