Covalently Linked Heterostructures of Phosphorene with MoS2/MoSe2 and Their Remarkable Hydrogen Evolution Reaction Activity

Hydrogen production by photochemical and electrochemical means is an important area of research related to renewable energy. 2D nanomaterials such as C 3 N 4 and MoS 2 have proven to be active for the hydrogen evolution reaction (HER). Phosphorene, a mono-elemental 2D layer of phosphorus, is known to catalyze the HER, but the activity is marginal. The use of phosphorene is also limited by its ambient instability. We have been able to prepare covalently cross-linked nanocomposites of phosphorene with MoS 2 as well as MoSe 2 . The phosphorene–MoS 2 nanocomposite shows excellent photochemical HER activity yielding 26.8 mmol h –1 g –1 of H 2, while only a negligible amount is produced by the physical mixture of phosphorene and MoS 2 . The phosphorene–MoS 2 composite also displays high electrochemical HER activity with an onset overpotential of 110 mV, close to that of Pt. The enhanced HER activity of the phosphorene–MoS 2 nanocomposite can be attributed to the ordered cross-linking of the 2D sheets, increasing the interfacial area as well as the charge-transfer interaction between phosphorene and MoS 2 layers. The phosphorene–MoSe 2 nanocomposite also exhibits good photochemical HER activity.