Gas Modulation Induced Ultra-Low Friction and Ultra-Strong Wear Resistance in Atomically Thin MoSe₂ Single Crystals

Area of Science:

• Materials Science
• Tribology
• Nanotechnology

Background:

• Atomically thin films are essential for micro-nano electromechanical systems (M/NEMS) lubrication.
• Achieving ultra-low friction and high wear resistance under ambient conditions remains a significant challenge.

Purpose of the Study:

• To develop a novel strategy for reducing friction and enhancing wear resistance in atomically thin films by tuning atmospheric composition.
• To investigate the tribological properties of monolayer (ML) and bilayer (BL) MoSe2 synthesized via chemical vapor deposition (CVD).

Main Methods:

• Synthesis of high-quality ML and BL MoSe2 single crystals using CVD.
• Tribological testing under varying atmospheric conditions (oxygen-to-nitrogen ratios).
• Experimental and molecular dynamics analyses to elucidate friction mechanisms.

Main Results:

• ML MoSe2 demonstrated ultra-low friction (COF = 0.0091) and super wear resistance (40,000 cycles@2.17 GPa) in atmosphere.
• Friction and wear properties were modulated by atmospheric composition, with pure nitrogen yielding optimal results.
• In pure N2, ML MoSe2 achieved a 50% lower COF (0.004) and nearly four times greater wear resistance (208,640 cycles@2.26 GPa).

Conclusions:

• Stronger N2 adhesion and weaker intermolecular interactions on ML MoSe2 surfaces promote ultra-low friction and super wear resistance.
• Atmospheric composition offers a new pathway for friction modulation in 2D materials.
• This strategy provides a promising approach for creating robust lubrication systems for M/NEMS applications.