Laser-Induced-Structural Transformation in Ti₃CNT_x MXene Monitored by Raman Spectroscopy with DFT Insight

MXenes are emerging 2D nanomaterials that have attracted growing attention for their highly tunable atomic structure, composition, and surface terminations. Raman analysis is widely used to study the structural and functional properties of nanomaterials, including MXenes (such as Ti₃C₂T_x and Ti₃CNT_x). Current literature on Ti₃CNT_x MXene shows inconsistent spectral interpretations and unclear guidance on optimal laser excitation conditions, and remains largely unexplored. To address these gaps, a comprehensive Raman spectroscopic study has been conducted for the microwave-assisted hydrothermally synthesized Ti₃CNT_x MXene using multiple excitation wavelengths (457, 514.5, 532, and 660 nm) and different laser powers. Our analysis identified threshold laser power levels for each wavelength, below which intrinsic MXene features are preserved and above which photothermal effects lead to the formation of amorphous carbon, TiO₂ phases, and N-doping. To support experimental observations and guide vibrational mode assignments, density functional theory calculations were performed on monolayer Ti₃CNT_x MXene functionalized with ─OH, ─F, and ─Cl groups. Additionally, we evaluated the environmental stability of Ti₃CNT_x MXene thin film under ambient conditions. The material exhibited excellent structural integrity with no significant spectral changes over more than a month. These findings pave the way for their integration into advanced solid-state laser-processed technologies such as  sensors, electrodes and electronics.