Synthesis and thermal stability of two-dimensional carbide MXene Ti3C2

• Ti3C2 from PLS-Ti3AlC2 was highly oriented compared to that from HP-Ti3AlC2.
• Small balls of possible AlF3 attached on the edge of MXene sheets were observed.
• MXene is thermally stable in Ar atmosphere up to 800 °C.
• A structure of nano-anatase on 2D Ti3C2 was formed by 200 °C oxidization.

We investigated the synthesis of quasi-two-dimensional carbide (Ti3C2), with the name of MXene, by immersing Ti3AlC2 in 40% or 49% hydrofluoric acid (HF) at 0 °C, 15 °C or 60 °C. The influences of time, temperature, and source of Ti3AlC2 on the synthesis were researched. It was found that Ti3C2 synthesized from pressureless synthesized Ti3AlC2 was highly oriented compared to that from hot-pressed Ti3AlC2. As-synthesized Ti3C2 could be further exfoliated by intercalation with urea, dimethylsulfoxide or ammonia. From the results of thermogravimetry and differential scanning calorimetry, Ti3C2 MXene with F/OH termination was found to be stable in argon atmosphere at temperature up to 800 °C. In oxygen atmosphere, at 200 °C, parts of MXene layers were oxidized to obtain an interesting structure: anatase nano-crystals were evenly distributed on 2D Ti3C2 layers. At 1000 °C, MXene layers were completely oxidized and anatase phase fully transformed to rutile in oxygen atmosphere.

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