Interlayer Friction Behavior of Molybdenum Ditelluride by AFM Nano-Manipulation

The interlayer friction behavior of two-dimensional transition metal dichalcogenides as crucial solid lubricants has attracted extensive attention in the field of tribology. In this study, the interlayer friction is measured by laterally pushing the MoTe₂ powder on the MoTe₂ substrate with the atomic force microscopy (AFM) tip, and density functional theory simulations are used to rationalize the experimental results. The results indicate that the friction coefficient of the 1T'-MoTe₂ /1T'-MoTe₂ interface is 2.025 × 10⁻⁴, which is lower than that of the 2H-MoTe₂ /2H-MoTe₂ interface (3.086 × 10⁻⁴), while the friction coefficient of the 1T'-MoTe₂ /2H-MoTe₂ interface is the lowest at 6.875 × 10⁻⁵. The lower interfacial friction of 1T'-MoTe₂/1T'-MoTe₂ compared to 2H-MoTe₂ /2H-MoTe₂ interface can be explained by the relative magnitudes of the ideal average shear strengths and maximum shear strengths obtained based on the interlayer potential energy, while the smallest interlayer friction of the 1T'-MoTe₂ /2H-MoTe₂ heterojunction is related to the weak interlayer electrostatic interaction and the weakening of the potential energy corrugation caused by the incommensurate contact. This work suggests MoTe₂ has comparable interlayer friction properties to MoS₂ and is expected to reduce interlayer friction in the future by inducing the 2H-1T' phase transition.

Keywords: Two-dimensional materials, MoTe₂, Interlayer friction, Interlayer shear strength.

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