One-pot synthesis of holey MoS ₂ nanostructures as efficient electrocatalysts for hydrogen evolution

In this work, highly porous MoS ₂ nanostructures have been synthesized via a one-pot and versatile calcination of cyanamide and (NH ₄ ) ₂ MoS ₄ precursors. At first, the thermal polymerization of cyanamide into carbon nitride suppresses the aggregation of MoS ₂ . Then, the thermal decomposition of the formed carbon nitride brings about plentiful pores with a size of 4–70 nm in MoS ₂ nanostructures, generating an extremely large specific surface area up to 311 m ² g ⁻¹ . Due to the high specific surface area and abundant exposed edge sites, the resultant porous MoS ₂ (p-MoS ₂ ) nanostructures exhibited outstanding electrochemical hydrogen evolution (HER) activity in a 0.5 M H ₂ SO ₄ aqueous solution. The onset overpotential and the overpotential at a current density of 10 mA/cm ² were as low as ∼30 mV and ∼130 mV, respectively, which is superior to the previously-reported MoS ₂ -based HER electrocatalysts.