Two-Dimensional Titanium Nitride (Ti₂N) MXene: Synthesis, Characterization, and Potential Application as Surface-Enhanced Raman Scattering Substrate

We report on the synthesis, characterization, and application of Ti 2 N (MXene), a two-dimensional transition metal nitride of M 2 X type. Synthesis of nitride-based MXenes (M n +1 N n ) is difficult due to their higher formation energy from M n +1 AN n and poor stability of M n +1 N n layers in the etchant employed, typically HF. Herein, the selective etching of Al from ternary layered transition metal nitride Ti 2 AlN (MAX) and intercalation were achieved by immersing the powder in a mixture of potassium fluoride and hydrochloric acid. The multilayered Ti 2 NT x (T is the surface termination) obtained was sonicated in DMSO and centrifuged to obtain few-layered Ti 2 NT x . MXene formation was verified, and the material was completely characterized by Raman spectroscopy, XRD, XPS, FESEM-EDS, TEM, STM, and AFM techniques. Surface-enhanced Raman scattering (SERS) activity of the synthesized Ti 2 NT x was investigated by fabricating paper, silicon, and glass-based SERS substrates. A Raman enhancement factor of 10 12 was demonstrated using rhodamine 6G as the model compound with 532 nm excitation wavelength. Detection of trace level explosives with a simple paper-based SERS substrate with Ti 2 N (MXene) as active material was also illustrated.