Decoration of the inert basal plane of defect-rich MoS2 with Pd atoms for achieving Pt-similar HER activity

Abstract

Outstanding hydrogen evolution reaction (HER) activity and stability are highly desired for transition metal dichalcogenide (TMD)-based catalysts as Pt substitutes. Here, we theoretically calculated and experimentally showed that adsorbing Pd atoms on the basal plane of defect-rich (DR) MoS₂ will effectively modulate the surface electronic state of MoS₂ while retaining its active sites, which greatly enhanced the HER activity. Three decoration strategies were used to implement this design: direct epitaxial growth, assembling spherical nanoparticles and assembling Pd nanodisks (NDs). The results showed that only Pd NDs are able to be site-specifically decorated on the basal plane of DR-MoS₂ through lamellar-counterpart-induced van der Waals pre-combination and covalent bonding. This Pd ND/DR-MoS₂ heterostructure exhibits exceptional Pt-similar HER properties with a low onset-overpotential (40 mV), small Tafel slope (41 mV dec⁻¹), extremely high exchange current density (426.58 μA cm⁻²) and robust HER durability. These results demonstrate a novel modification strategy by a lamellar metallic nanostructure for designing excellent layered TMD-based HER catalysts.