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

Abstract

We report on the synthesis, characterization, and application of Ti₂N (MXene), a two-dimensional transition metal nitride of M₂X type. Synthesis of nitride-based MXenes (M_n+1N_n) is difficult due to their higher formation energy from M_n+1AN_n and poor stability of M_n+1N_n layers in the etchant employed, typically HF. Herein, the selective etching of Al from ternary layered transition metal nitride Ti₂AlN (MAX) and intercalation were achieved by immersing the powder in a mixture of potassium fluoride and hydrochloric acid. The multilayered Ti₂NT_x (T is the surface termination) obtained was sonicated in DMSO and centrifuged to obtain few-layered Ti₂NT_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 Ti₂NT_x was investigated by fabricating paper, silicon, and glass-based SERS substrates. A Raman enhancement factor of 10¹² 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 Ti₂N (MXene) as active material was also illustrated.