Hydrogen has emerged as a promising renewable energy since it is one of the cleanest fuels and has a large energy capacity. Two-dimensional (2D) molybdenum disulfide (MoS2) nanosheets have potential as substitutes for traditional platinum (Pt) catalysts in the production of hydrogen through the hydrogen evolution reaction (HER). However, the poor electron transport severely limits the application of MoS2 catalysts. 
Electron transport is a crucial factor that affects the activity of a catalyst. Normally, MoS2 nanosheets contain a mixed metallic 1T phase and semiconducting 2H phase. The latter one constrains the conduction of MoS2 nanosheets.
The complications of carbon
In order to attain a faster charge transport of MoSx-based catalysts, carbon-based nanomaterials are used as conductive networks or supporting templates. However, the preparation of these composite materials contains complicated multiple-steps, either with high temperatures, or the catalytic systems lead to relatively low catalyst loadings.
Electron transport pathways
Researchers from Zhejiang University in China develop a facile method to prepare a high-performance catalytic system comprising 2D MoS2 nanosheets and single-walled carbon nanotubes (SWCNTs) for HER. Because of their excellent conductivity and flexibility, SWCNTs can serve as efficient electron transport pathways in the hybrid catalytic system.
Compared to pure MoS2 counterpart catalysts, the composite system exhibits dramatically enhanced electrocatalytic activity. With a low onset overpotential and a Tafel slope of 40.82 mV/decade, these are among the lowest values for MoS2-based catalysts reported so far 