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-VMo) by immersing a single Ni atom-decorated MoS2 (Ni-MoS2) into K3[Co(CN)6] solution. Subsequently, NiCoP-MoS2-VMo 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-VMo nanosheets in NiCoP-MoS2-VMo, 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-VMo has enhanced chemical adsorption for H* (on MoS2-VMo) 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.