Optimization of etching and sonication time to prepare monolayer Ti3C2Tx MXene flakes: A structural, vibrational, and optical spectroscopy study

Abstract

Two-dimensional (2D) Ti3C2Tx MXene and its heterostructure exhibit promising performances in several applications such as energy storage, optoelectronics, electrocatalysis, water purification, biomedical, etc. Our investigation shows that an etching duration of 24 h is sufficient to remove Al layers from Ti3AlC2 and to obtain a well-separated accordion-like structure. Different lateral size monolayer MXene flakes ranging from 2 μm to 35 nm are obtained by tuning the sonication time from 2 to 8 h. The monolayer nature of the flakes is confirmed by both Atomic Force Microscope (AFM) and Transmission Electron Microscope (TEM). Raman vibrational modes and X-ray photoelectron spectroscopy (XPS) show that the flakes are containing –O, –F, and –OH functional groups. A unique type of absorption spectra is observed that comes from both interband and intraband transition. An in-depth structural, vibrational, and optical property study gives a clear idea to use these flakes for heterostructure formation with other materials for various applications.