Electrocatalytic hydrogen evolution on the noble metal-free MoS ₂/carbon nanotube heterostructure: a theoretical study

Abstract

Molybdenum disulfide (MoS ₂) is considered as a promising noble-metal-free electrocatalyst for the Hydrogen Evolution Reaction (HER). However, to effectively employ such material in the HER process, the corresponding electrocatalytic activity should be comparable or even higher than that of Pt-based materials. Thus, efforts in structural design of MoS ₂ electrocatalyst should be taken to enhance the respective physico-chemical properties, particularly, the electronic properties. Indeed, no report has yet appeared about the possibility of an HER electrocatalytic association between the MoS ₂ and carbon nanotubes (CNT). Hence, this paper investigates the synergistic electrocatalytic activity of MoS ₂/ CNT heterostructure for HER by Density Functional Theory simulations. The characteristics of the heterostructure, including density of states, binding energies, charge transfer, bandgap structure and minimum-energy path for the HER process were discussed. It was found that regardless of its configuration, CNT is bound to MoS ₂ with an atomic interlayer gap of 3.37 Å and binding energy of 0.467 eV per carbon atom, suggesting a weak interaction between CNT and MoS ₂. In addition, the energy barrier of HER process was calculated lower in MoS ₂/CNT, 0.024 eV, than in the MoS ₂ monolayer, 0.067 eV. Thus, the study elaborately predicts that the proposed heterostructure improves the intrinsic electrocatalytic activity of MoS ₂.