Activated MoS₂ by Constructing Single Atomic Cation Vacancies for Accelerated Hydrogen Evolution Reaction

Regulating the electronic structure of MoS₂ by constructing cationic vacancies is an effective method to activate and improve its intrinsic properties. Herein, we synthesize the MoS₂-based composite with abundant single atomic Mo cation vacancies through uniformly loading nickel-cobalt-Prussian blue analogues (NiCoPBA) (NiCoPBA-MoS₂-V_Mo) by immersing a single Ni atom-decorated MoS₂ (Ni-MoS₂) into K₃[Co(CN)₆] solution. Subsequently, NiCoP-MoS₂-V_Mo with improved conductivity is obtained by phosphating the composite as a high-efficiency hydrogen evolution reaction (HER) catalyst. Experiments and theoretical calculations indicate that the electrons of NiCoP are spontaneously transferred to the substrate MoS₂-V_Mo nanosheets in NiCoP-MoS₂-V_Mo, and the moderately oxidized NiCoP is beneficial to the adsorption of OH*. Meanwhile, the mono-atomic Mo cation vacancies of the catalyst modulate the electronic structure of S, optimizing the adsorption of hydrogen in the reaction process. Therefore, NiCoP-MoS₂-V_Mo has enhanced chemical adsorption for H* (on MoS₂-V_Mo) and OH*(on NiCoP), expediting the water-splitting step and HER catalysis, and benefiting from the regulation of the electronic structure induced by the construction of metallic Mo vacancies in MoS₂, the as-prepared catalyst displays an overpotential of only 67 mV at 10 mA cm^-2 with long-term stability (no current decay over 20 h). This work affords not only a kind of efficient HER catalysts but also a new valuable route for developing inexpensive and high-performance catalysts with single atomic cation vacancies.