Controlled Covalent Functionalization of 2H‐MoS2 with Molecular or Polymeric Adlayers.

Air-stable 2D materials are relatively inert, which makes their chemical modification difficult. In the case of MoS2, the semiconducting 2H-MoS2 is much less reactive than its metallic counterpart, 1T-MoS2. As a consequence, there are very few methods for the covalent modification of 2H-MoS2. An ideal method for the functionalization of 2H-MoS2 should be mild, without introduction of a large number of defects, and versatile, allowing for the decoration with as many different functional groups as possible. Herein, a comprehensive study on the covalent functionalization of 2H-MoS2 with maleimides is presented. The use of a base leads to the in situ formation of a succinimide polymer layer covalently connected to MoS2. In the absence of base, functionalization stops at the molecular monolayer. The protocol is mild (room temperature), fast (nearly complete in 1h), and very flexible (10 different maleimides tested). In practical terms, the procedures described here allow for the decoration of 2H-MoS2 with polymers or molecules, and with a wide range of functional groups for subsequent modification. Conceptually, the spurious formation of an organic polymer might be general to other methods of functionalization of 2D materials, where a large excess of molecular reagents is typically used.