Nanostructured catalyst assembled from CNTs, NiSe2 nanoparticles, and 2D Ni-MOF nanosheets for electrocatalytic hydrogen evolution reaction.

The hydrogen evolution reaction (HER) has an important role in H₂ production. Two-dimensional metal–organic framework nanosheets (2D MOF NSs) have become durable and efficient electrocatalysts for the HER due to their ultrathin thickness and large surface area, but such nanosheets are usually less conductive and tend to aggregate, which greatly affect their electrocatalytic efficiency. The introduction of carbon nanotubes (CNTs) on the substrate nanosheets may prevent the aggregation of nanosheets, enhance their conductivity and bring the synergistic effect of multilevel nanostructures. Herein, we propose a simple and unique strategy to yield electrocatalysts with multilevel nanostructures, in which CNTs are grown in situ from 2D Ni-MOF NSs through calcination. Ni nanoparticles (NPs) encapsulated at the tips of CNTs can be readily converted into NiSe₂ NPs after selenization. The optimized NiSe₂-NPs/CNTs/Ni-MOF NS catalyst exhibits an enhanced electrocatalytic HER performance. Furthermore, the two-electrode system that uses NiSe₂-NPs/CNTs/Ni-MOF NSs/NF as both the anode and the cathode shows good electrocatalytic activity toward overall water splitting in 1.0 M KOH. This report provides a new insight into the synthesis of CNTs from simple MOFs and multilevel nanostructures composed of metal chalcogenide NPs, CNTs and 2D Ni-MOFs for efficient electrocatalytic HER. [ABSTRACT FROM AUTHOR]