Strongly coupled MoS2 nanoflake–carbon nanotube nanocomposite as an excellent electrocatalyst for hydrogen evolution reaction

Abstract

As a promising non-precious metal electrocatalyst for the hydrogen evolution reaction (HER), MoS₂ suffers from impeded electrical conductivity and scarce active sites. This tricky situation can be ameliorated but not eliminated by the simple involvement of nanocarbons. Herein, a leaves-and-branch structure of strongly coupled and porous MoS₂–carbon nanotube (CNT) nanocomposite was synthesized, where few-layer MoS₂ nanoflakes are anchored radially and intimately on the surface of CNT. Mo–O–C has been unveiled to be the bridge between these two phases and a sandwich-like structure was proposed for the interface within the strongly coupled MoS₂–CNT. This genuine nanocomposite exhibits remarkably improved electrocatalytic activity towards HER, reaching −850 mA cm_geo⁻² with the expense of only 290 mV of overpotential and maintaining a low Tafel slope of 47 mV per decade even under a current density of 100 mA cm_geo⁻². After detailed analysis, this surging activity has been ascribed not so much to the simple addition of the properties of MoS₂ and CNT, but to a strong interfacial attachment between them which not only stabilizes tiny and edge-terminated MoS₂ nanoflakes, but also constructs a three dimensional hierarchical structure to boost electron and mass transfer during the HER operation.