Advancements in the Nanotribology of Two-Dimensional Layered Materials

Dear Colleagues,

A central theme in current tribology research is the investigation of novel two-dimensional (2D) nanomaterials that can promote ultralow sliding friction and minimal wear in real-world applications. In this context, 2D layered materials such as graphene, transition metal dichalcogenides, and hexagonal boron nitride are being intensively studied. Compared to their bulk counterparts, 2D materials offer the advantage of easy deposition and conformation to surfaces due to their greater flexibility. Additionally, they exhibit unique nanomechanical properties at the atomic thickness limit. The frictional behaviour of 2D materials is influenced by several factors, including their thickness and interactions with the supporting substrates and with the ambient environment. The body of knowledge in this field is rapidly expanding, aiming for a comprehensive characterization of the nanotribology of 2D materials. This progress goes side by side with the preparation of high-quality samples with tailored thickness and extension, improved methods for creating liquid dispersions using scalable fabrication techniques, and the discovery of novel 2D materials with new compositions, structures, and functionalities. As research progresses, 2D materials are expected to revolutionize tribological applications across various industries, including those based on micro- and nanoelectromechanical systems (MEMS/NEMS).

Atomic Force Microscopy (AFM), particularly in its Friction Force Microscopy (FFM) mode, enables researchers to investigate friction at atomic and molecular scales. FFM offers unique insights into the fundamental processes that govern the nanotribological response of contact junctions based on 2D materials. By focusing on single-asperity contacts, FFM simplifies friction studies and helps understand the behaviour of 2D materials under specific working conditions. It separately addresses the influence of external parameters such as load, velocity, temperature, and superimposed electric fields.

This Special Issue aims to cover the latest developments in the nanotribological characterization of 2D layered materials using FFM. Original research articles and reviews are welcome. Research areas may include (but are not limited to) the following:

• Nanotribology of 2D materials, as investigated by FFM and colloidal probe FFM techniques;
• FFM characterization of 2D materials heterostructures, including friction control by strain effects and friction of Moiré superstructures;
• Functionalization of AFM probes with 2D materials to systematically characterize the nanotribology of homo- and hetero-junctions;
• Nanoscale/mesoscale friction explored through the FFM-assisted manipulation of nanomaterials and micro-objects on 2D materials platforms;
• Electronic control of friction, e.g., by tuning surface trapped charges, doping charge levels, or strain levels in nanoscale/mesoscale contact junctions based on 2D materials.
• Impact of structural or chemical defects on the nanotribology of 2D materials;
• Nanotribology of solution-processed single-layer and few-layer 2D flakes.

I look forward to receiving your contributions.

Dr. Renato Buzio
Guest Editor

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• atomic force microscopy
• friction force microscopy
• 2D materials and flakes
• layered materials
• nanotribology
• superlubricity
• friction control
• manipulation
• liquid dispersions