Superlubric Sliding of Graphene Auto-Kirigami with Interfaces Containing Self-Assembled Stripe-Pattern Adsorbates

Area of Science:

• Materials Science
• Tribology
• Condensed Matter Physics

Background:

• Van der Waals heterostructures exhibit unique properties due to stacked 2D materials.
• Superlubricity, characterized by ultra-low friction between incommensurate atomic planes, enables phenomena like graphene nanostructure self-assembly.
• Adsorbate stripe structures are commonly found on graphene surfaces under ambient conditions.

Purpose of the Study:

• To investigate the stability and impact of ubiquitous adsorbate stripe structures on the superlubricity of twisted graphene interfaces.
• To determine if direct atomic incommensurate contact is a prerequisite for achieving ambient superlubricity in 2D materials.

Main Methods:

• Experimental investigation of twisted graphene layers under ambient conditions.
• Analysis of the interface structure and frictional properties.
• Estimation of the frictional shear strength of the interface.

Main Results:

• A stable adsorbate stripe structure was observed within the interface of sliding twisted graphene layers.
• The interface maintained an exceptional superlubricious state despite the presence of these adsorbate stripes.
• The estimated upper bound frictional shear strength was found to be 10 kPa.
• Direct atomic incommensurate contact was demonstrated to be unnecessary for ambient superlubricity.

Conclusions:

• Ambient superlubricity in 2D materials can be achieved even with intercalated adsorbate structures.
• The presence of stable adsorbate stripes at the interface does not preclude ultra-low friction.
• Future research on 2D heterostructure interfaces should account for the influence of these persistent adsorbate structures.