Topotactic transition of Ti4AlN3 MAX phase in Lewis acid molten salt

MAX phases and its derived two-dimensional MXenes have attracted considerable interest because of their rich structural chemistry and multifunctional applications. Lewis acid molten salt route provides an opportunity for structure design and performance manipulation of new MAX phases and MXenes, Although a series of new MAX phases and MXenes were successfully prepared via Lewis acid melt route in recent years, few work is explored on nitride MAX phases and MXenes. Herein, a new copper-based 413-type Ti 4 CuN 3 MAX phase was synthesized through isomorphous replacement reaction using Ti 4 AlN 3 MAX phase precursor in molten CuCl 2 . In addition, it was found that at high temperature Ti 4 N 3 Cl x MXene will transform into two-dimensional cubic TiN α nanosheets with improved structural stability.