The effect of fluoride based salt etching in the synthesis of MXene

Abstract

Here we reported the effect of fluoride-based salt etching in the synthesis of Ti3C2 MXene by etching Ti3AlC2 MAX phase precursor. Lithium fluoride (LiF) and ammonium fluoride were the fluoride-based salts were chosen as an etching agent in this study. The optimum etchant concentration and etching temperature of the MAX phase were evaluated. The presence of aluminium etched was determined by using the Inducted Couple Plasma Optical Emission Spectrometry (ICP-OES). The initial concentration of aluminium in Ti3AlC2 precursor was estimated based on the data from Energy Dispersive X-Ray Analysis (EDX). The study shows that the optimum etchant concentration of LiF is 5M and NH4F is 3M. Room temperature is the optimum etching temperature due to the exothermic reaction of the process. Compared to LiF, NH4F is the preferred salt for in-situ HF fluoride-based salt etchant due to the capability of the salt to etch the maximum amount of Al at a low concentration of 3M within 24 hours at room temperature.