One-dimensional, space-confined, solid-phase growth of the Cu₉S₅@MoS₂ core-shell heterostructure for electrocatalytic...

Binary transition metal chalcogenide core-shell nanocrystals are considered the most promising nonprecious metal catalysts for large-scale industrial hydrogen production. Herein, we report a one-dimensional, space-confined, solid-phase strategy for the growth of a Cu₉S₅@MoS₂ core-shell heterostructure by combining electrospinning and chemical vapor deposition methods. The Cu₉S₅@MoS₂ core-shell nanocrystals were synthesized in situ on carbon nanofibers (Cu₉S₅@MoS₂/CNFs) by an S vapor graphitization process. Tuning of the MoS₂ shell numbers can be controlled by changing the mass ratio of the Cu and Mo precursors. We experimentally determined the effects of the thickness of the MoS₂ shell on the electrocatalytic activity for the hydrogen evolution reaction (HER) in acidic and alkaline solutions. When the mass ratio is 3:1, the Cu₉S₅@MoS₂/CNFs show the fewest MoS₂ shells with just 1-2 layers each and exhibit the best HER performance with small overpotentials of 116 mV and 114 mV in acidic and alkaline solutions, respectively, at a current density of 10 mA cm^-2. The core shell structures, with their unique Cu-S-Mo nanointerfaces, could enhance the electron transfer and surface area, thus increasing the performance of the HER. This work provides a facile method to design unique core shell assemblies in one-dimensional nanostructures.