The XRD patterns shown in Figure . Figure (a) is the XRD pattern of Ti3C2 MXene in Reference . Figure is the XRD pattern of the sample etched in HF solution at 30 °C for 1 h. Figure ) is the XRD patterns of the sample treated in KF+HCl solution at 60 °C for 24 h. Figure ) is XRD pattern of commercial TiN powders (TiN, >99 wt.%; Macklin, China). The diffraction peaks of TiN from PDF card No. 65-0715 is shown in Figure . Figure (f) is the XRD pattern of Ti2AlN powders before etching.