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

Area of Science:

• Materials Science
• Nanotechnology
• Organic Chemistry

Background:

• Air-stable 2D materials, such as molybdenum disulfide (MoS2), are often chemically inert, hindering their modification.
• The semiconducting 2H-MoS2 phase is particularly unreactive, limiting covalent functionalization methods.
• Existing methods often introduce defects or lack versatility for diverse functional group attachment.

Purpose of the Study:

• To develop a mild, versatile, and defect-minimizing covalent functionalization strategy for 2H-MoS2.
• To explore the use of maleimides for modifying MoS2 surfaces.
• To investigate the influence of reaction conditions, such as the presence of a base, on the functionalization outcome.

Main Methods:

• Covalent functionalization of 2H-MoS2 using maleimides under varying conditions.
• Utilized triethylamine (Et3N) as a base to promote in situ polymer formation.
• Systematically tested different solvents and maleimide derivatives to assess reaction flexibility.

Main Results:

• In situ formation of a succinimide polymer layer covalently attached to MoS2 was achieved in the presence of a base.
• Functionalization remained at the molecular level without the base.
• The protocol demonstrated mild conditions (room temperature), rapid kinetics (1 hour), and broad applicability (11 solvents, 10 maleimides).

Conclusions:

• A novel, efficient, and flexible covalent functionalization method for 2H-MoS2 using maleimides has been established.
• The reaction allows for controlled decoration of MoS2 with polymers or molecules, enabling subsequent modifications.
• The observed polymer formation may be a general phenomenon in 2D material functionalization with excess reagents.