Anisotropic frictional properties between Ti3C2Tx MXene/SiO2 layer-dependent heterojunctions

Abstract

Two-dimensional (2D) Ti3C2Tx MXene sheet possesses its interesting electrical and optical properties and has thus aroused widespread interest in a wide range of flexible optoelectronic device applications. A clear understanding of the friction behavior and performance, of MXene and other transparent materials (e.g., SiO2) will enable these promising applications. In this study, the frictional behaviors between the SiO2 (100) plane and the MXene sheet have been measured by a lateral force atomic force microscopy (AFM), based on the realization of the friction experiments in the single crystal heterojunction. The results on the two-dimensional single–layer interface between MXene and SiO2 clearly show that the corresponding heterostructure owns a strong friction anisotropy with a six-fold symmetry. The friction coefficient for the misaligned contact is 0.067, while it is 0.031 for the aligned one. We find that the measurement of friction anisotropy is highly related to the number of atomic layers of MXene. The increase of the layer number is found to significantly reduce the friction anisotropy and beyon 10 layers it is no longer related to the thickness. These findings will have general applicability and can be used in other MXene heterojunction configurations to realize the advantages of adaptive nanodevices and the development of flexible optoelectronics.