Strategies for Optimizing Etching and Delamination Toward High-Quality Ti₃C₂T_x MXenes

MXenes, two-dimensional (2D) transition metal carbides, nitrides, or carbonitrides, are a rapidly growing family of nanomaterials that have potential uses ranging from energy storage, catalysis, and electromagnetic interference shielding to medical applications. To recognize these applications, it is known that etching and subsequent delamination play a vital role in the quality and scalability of MXenes. Here, we present the experimental strategies to synthesize the most studied MXene, Ti₃C₂T<i>_x</i>, using different precursor powder, etching conditions, and delamination methods. For etching, we compare different etchants, including hydrofluoric acid (HF)/hydrochloric acid (HCl) mix and HCl/lithium fluoride (LiF) mix, and conditions such as time and temperature. For delamination, we investigate the effect of time, temperature, and environment (air or argon) on the quality of the Ti₃C₂T<i>_x</i>MXene. We analyze the resultant Ti₃C₂T<i>_x</i>MXene using x-ray diffraction, scanning electron microscopy, and electrical conductivity to illustrate the relation between different synthesis methods on the quality of single-to-few layer MXene flakes of Ti₃C₂T<i>_x</i>. With this detailed synthesis study on etching and delamination methods, we suggest updated optimal parameters for the synthesis of high quality Ti₃C₂T<i>_x</i> MXenes.