Vertically Aligned Interlayer Expanded MoS₂ Nanosheets on a Carbon Support for Hydrogen Evolution Electrocatalysis

This work describes the facile microwave synthesis of interlayer expanded, nanosized MoS₂ sheets that are vertically aligned on a well-conducting reduced graphene (rGO) support, as confirmed by X-ray diffraction, Raman and X-ray photoelectron spectroscopy, scanning electron microscopy with energy dispersive X-ray analysis, and high-resolution transmission electron microscopy. Such structure has been predicted to be highly favorable for efficient electrocatalysis of hydrogen evolution by MoS₂ but could not be achieved until now. Films deposited from the microwave-synthesized MoS₂-rGO composites demonstrate outstanding and stable hydrogen evolution performance in acidic solution. These catalysts exhibit an exchange current density as high as 1.0 ± 0.2 A g^-1 _MoS2-rGO, sustain a current density of 10 mA cm^-2 (36 A g^-1 _MoS2-rGO) at an overvoltage of 0.104 ± 0.002 V, and maintain steady performance for many hours. Importantly, our simple synthesis affords several advantages over more sophisticated methods used previously to prepare MoS₂ catalysts.