Structural Engineering of Nitrogen-Doped MoS2 Anchored on Nitrogen-Doped Carbon Nanotubes towards Enhanced Hydrogen Evolution Reaction

Molybdenum disulfide (MoS2) has emerged as an attractive non-noble-metal electrocatalyst for hydrogen evolution reaction (HER), but its performance is limited by scarce active sites and poor conductivity. Herein, we construct a hetero-structure of nitrogen-doped MoS2 ultrathin nanosheets anchored on nitrogen-doped multi-walled carbon nanotubes (N-MoS2/N-CNTs) using urea as N-doping reagent. It is demonstrated that the N species can expand the interlayer spacing of MoS2 and in-situ substitute the S atoms in MoS2 lattices to create more structural defects, enabling highly exposed basal plane/edge sites. Simultaneously, N species in CNTs favor the interface coupling between N-MoS2 and N-CNTs, which can maintain structural stability and accelerate electron/proton reaction kinetics. Consequently, N-MoS2/N-CNTs exhibits the in-depth enhancement of HER activity with a low onset potential (77 mV), small Tafel slope (40.5 mV dec(-1)) and excellent cycling stability. Furthermore, the essential relationship between the N-doping concentration and HER activity of N-MoS2/N-CNTs was demonstrated.