A key parametric study of ultrasonic exfoliation of 2D TiB₂ using DI water as a unique medium

Liquid Phase Exfoliation (LPE) is a very effective technique for the synthesis of few layered two dimensional (2D) nanosheets. There is a surge to find environment friendly solvents for efficient exfoliation of layered materials to produce 2D nanosheets. TiB₂ is an important layered material with very little reported work on its 2D nanosheets. The present work is about successful LPE of TiB₂ using deionized (DI) water as a clean, green and low cost dispersion medium to make TiB₂ nanosheets. The impact of ultrasonication conditions i.e. input power and treatment duration for efficient synthesis of few layered 2D nanosheets in DI water is studied by Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). It is found that by increasing input power, the layer thickness is reduced from bulk to 34 nm with lateral dimensions as huge as up to 5 μm. The increased treatment duration has further reduced the layer thickness to 21 nm associated with a decrease in lateral dimensions to about 1 μm. The mechanism of variation in the aspect ratio of the 2D nanosheets with ultrasonication power and treatment duration is explained. The optimum conditions for the fabrication of high aspect ratio 2D nanosheets of TiB₂ owe to a greater acoustic cavitation intensity, an optimum treatment duration and a homogenous distribution of the cavitation events while using an appropriate size of the sonotrode in the sonicated volume during ultrasonication.