In-situ formation and integration of graphene into MoS2 interlayer spacing: expansion of interlayer spacing for superior hydrogen evolution reaction in acidic and alkaline electrolyte

For the commercial-scale of hydrogen production from water-splitting, developing earth-abundant and competitive price catalysts is highly demanding, but it is challenging to replace the noble metal-based state-of-the-art catalysts. Herein, we report MoS2@graphene (MoS2@Gr) heterostructures materials as a promising hydrogen evolution reaction (HER) electrocatalyst, which is synthesized via in-situ formation and integration of graphene into the interlayer spacing of MoS2, thereby exposing the HER active edge sites via widening of the interlayer spacing. Compared to the pristine MoS2, the MoS2@Gr exhibits a superior HER activity having an overpotential of 120 mV vs. RHE to drive the current density of 10 mA cm(-2) with a small Tafel slope of 72 mV dec(-1) in 0.5 M H2SO4 solution. In addition, the MoS2@Gr catalyst requires only an overpotential of 170 mV vs. RHE in 1 M KOH electrolyte to drive the HER current densities of 10 mA cm(-2) with a smaller Tafel slope of 51 mV dec(-1). Moreover, the MoS2@Gr catalyst presents long-term durability against HER in both acidic and alkaline electrolytes. [GRAPHICS] .