Fabrication and thermal stability of NH4HF2-etched Ti3C2 MXene

MXene , a new family of 2D transition metal carbides and carbonitrides , has been proved to possess excellent electrical conductivity and hydrophilicity. In this work, a single-step method to produce the larger interplanar spacing 2D MXene Ti 3 C 2 by etching Ti 3 AlC 2 with NH 4 HF 2 was demonstrated, and the optimal reaction conditions between Ti 3 AlC 2 and NH 4 HF 2 were systematically researched. The morphology and microstructure of samples were characterized by scanning electron smicroscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD). The thermal stability of Ti 3 C 2 was investigated by the thermogravimetry (TG) and differential thermal analyzer (DTA). It was found that the lattice parameter c of obtained Ti 3 C 2 was up to 24.9   Å, and the larger interplanar spacing Ti 3 C 2 was more stable than the sample exfoliated by HF. The transition temperature in air from NH 4 HF 2 -etched Ti 3 C 2 to anatase TiO 2 thoroughly is more than 500   ℃, and the multilayered structure of Ti 3 C 2 could be well retained even afer 900   ℃ heat treatment, while the value of HF-etched Ti 3 C 2 is less than 350   ℃. This work is important for exploring a safe synthesis method and well understanding the thermal stability of 2D MXene materials.