Layer-Dependent Nanowear of Graphene Oxide.

Area of Science:

• Materials Science
• Nanotechnology
• Tribology

Background:

• Graphene oxide (GO) exhibits thickness-dependent mechanical properties.
• Understanding wear mechanisms in 2D materials is crucial for their application.

Purpose of the Study:

• To investigate the non-monotonic layer-dependence of nanowear resistance in GO nanosheets.
• To elucidate the role of substrate surface energy and interfacial interactions in GO wear.
• To propose strategies for improving the antiwear properties of 2D layered materials.

Main Methods:

• Experimental nanowear testing of GO nanosheets on different substrates (silicon oxide, H-DLC).
• Varying GO thickness from ~0.9 nm to ~14.5 nm.
• Density functional theory (DFT) calculations to model interfacial charge transfer and adhesion.

Main Results:

• GO nanowear resistance exhibited a non-monotonic trend with thickness, decreasing then increasing, with a critical thickness around 3.6 nm.
• Wear modes shifted from overall removal to layer-by-layer removal with increasing GO thickness.
• Substrate surface energy significantly influenced wear resistance, particularly for few-layer GO, due to substrate-dependent adhesion.

Conclusions:

• The wear resistance of GO is strongly influenced by its thickness and the substrate's surface energy.
• Interfacial charge transfer and adhesive strength play key roles in substrate-dependent wear.
• Tuning GO thickness and interfacial interactions provides a pathway to enhance the antiwear performance of 2D materials.