Heterostructural MoS2/NiS nanoflowers via precise interface modification for enhancing electrocatalytic hydrogen evolution

Abstract

Currently, two-dimensional (2D) layered transition metal chalcogenides (TMCs), especially MoS₂, are attracting widespread attention in the field of water electrolysis. Unfortunately, the catalytic activity of MoS₂ is limited to a few edge sites and by its low conductivity. Herein, MoS₂/NiS heterostructures possessing a flower-like morphology were constructed via an accurate thermal treatment process to realize precise interface modification. As expected, through the adjunction of a certain amount of polyvinylpyrrolidone, NiS grew uniformly on the surface of MoS₂ nanosheets, thereby forming a large number of visual lattice fringes with a specific interplanar spacing, which promoted a higher electron-transfer efficiency. The better electron-transfer efficiency resulted in a better hydrogen evolution reaction performance, providing an overpotential of 158 mV at 10 mA cm⁻¹, a Tafel slope of 128.1 mV dec⁻¹, and significantly long-term durability. Moreover, density functional theory calculation also showed that the precise interface modification of MoS₂/NiS heterostructure exhibited more occupations at the Fermi level, which improved the electrical conductivity. Additionally, the MoS₂/NiS catalysts achieved a moderately lower hydrogen adsorption energy (ΔG_H*), indicating that it had better catalytic hydrogen evolution performance. This work can be extended to design other catalytic materials and for understanding reactions in the fields of energy conversion through theoretical calculations.