2D Ti3C2Tz MXene Synthesized by Water-free Etching of Ti3AlC2 in Polar Organic Solvents

Abstract

Summary The first MXene discovered, Ti3C2Tz, was synthesized by etching of the parent MAX phase, Ti3AlC2, in a solution of concentrated hydrofluoric acid. Since then, several other ways of synthesizing MXenes have been reported, such as electrochemical etching in various electrolytes, high-temperature alkali treatment, molten salt synthesis, etc. The majority of these etching methods, however, use water as their main solvent, limiting direct use of MXenes in water-sensitive applications. In this work, we show that it is possible to etch, and delaminate, MXenes in the absence of water, by using organic polar solvents in the presence of ammonium dihydrogen fluoride. We further show that by using this etching method, it is possible to obtain Ti3C2Tz flakes rich in fluorine terminations. We also demonstrate that electrodes made from Ti3C2Tz etched in propylene carbonate resulted in Na-ion battery anodes with double the capacity to those etched in water.