Effect of HF Concentration on the Structural, Morphological, and Electrical Properties of Ti₃ C₂ T_x MXene Prepared by Microwave-Assisted Etching

Two-dimensional MXenes have emerged as a versatile class of materials for energy storage, electronics, and catalysis owing to their high electrical conductivity, tunable surface chemistry, and layered structure; however, the controlled synthesis of Ti₃C₂T_x MXene with well-defined morphology and stable surface chemistry remains a major challenge, as etching conditions strongly influence structural integrity, degree of exfoliation, and functional performance. In this study, the morphological, structural, and functional evolution of Ti₃C₂ T_x MXene materials was systematically investigated by applying hydrofluoric acid (HF) etching at varying concentrations (6 %, 12 %, 24 %, 36 %, and 48 %) using microwave-assisted method. The impact of etching intensity on Al removal, layer delamination, and surface functionalization was examined through a multitechnique characterization approach including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDS). The results reveal that an HF concentration of 24 % achieves efficient Al extraction while preserving the Ti– C framework, yielding well-exfoliated and structurally stable MXene sheets. Lower HF concentrations (6 % and 12 %) lead to incomplete etching and limited exfoliation, whereas higher concentrations (36 % and 48 %) cause over-etching and pronounced structural degradation. These findings underscore the critical role of etching conditions in tuning MXene morphology and functional properties. The ability to balance surface termination control and structural integrity via gradient etching is particularly relevant for the use of Ti₃C₂T_x MXenes as conductive electrodes and interfacial layers in photovoltaic and other energy-conversion devices.