Interlayer friction behavior of molybdenum ditelluride with different structures

The interlayer friction behavior of two-dimensional transition metal dichalcogenides (TMDCs) 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 microscope (AFM) tip, and density functional theory (DFT) simulations are used to rationalize the experimental results. The experimental 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 considering the relative magnitudes of the ideal average shear strengths and maximum shear strengths based on the interlayer potential energy. Additionally, the smallest interlayer friction observed at the 1T'-MoTe₂/2H-MoTe₂ heterojunction is attributed to the weak interlayer electrostatic interaction and reduction in potential energy corrugation caused by the incommensurate contact. This work suggests that 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.