Biocompatible and Oxidation‐Resistant Ti ₃ C ₂ T _x MXene with Halogen‐Free Surface Terminations

Surface chemistry influences not only physicochemical properties but also safety and applications of MXene nanomaterials. Fluorinated Ti 3 C 2 T x MXene, synthesized using conventional HF‐based etchants, raises concerns regarding harmful effects on electronics and toxicity to living organisms. In this study, well‐delaminated halogen‐free Ti 3 C 2 T x flakes are synthesized using NaOH‐based etching solution. The transversal surface plasmon mode of halogen‐free Ti 3 C 2 T x MXene (833 nm) confirmed red‐shift compared to conventional Ti 3 C 2 T x (752 nm), and the halogen‐free Ti 3 C 2 T x MXene has a different density of state by the high proportion of –O and –OH terminations. The synthesized halogen‐free Ti 3 C 2 T x exhibits a lower water contact angle (34.5°) and work function (3.6 eV) than those of fluorinated Ti 3 C 2 T x (49.8° and 4.14 eV, respectively). The synthesized halogen‐free Ti 3 C 2 T x exhibits high biocompatibility with the living cells, as evidenced by no noticeable cytotoxicity, even at very high concentrations (2000 µg mL⁻ 1 ), at which fluorinated Ti 3 C 2 T x caused ≈50% reduction in cell viability upon its oxidation. Additionally, the oxidation stability of halogen‐free Ti 3 C 2 T x is enhanced unexpectedly, which cumulatively provides a good rationale for pursuing the halogen‐free routes for synthesizing MXene materials for their uses in biomedical and therapeutic applications.