Effect of Synthesis Conditions on the Morphology and Electrochemical Properties of Nb ₂ CT _x MXenes

Niobium carbide (Nb 2 CT x ) MXene has recently gained increasing attention for applications in energy storage, catalysis, and electronics. However, despite many studies on the properties of this material, a systematic investigation linking the synthesis conditions to morphology, stability, and electrochemical properties of single-layer Nb 2 CT x are still lacking. Here we report a comprehensive study establishing synthesis–structure–property relationships for Nb 2 CT x . Nb 2 AlC MAX phase was etched in two different etchants, followed by delamination through intercalation of different organic cations. The etchant composition strongly influenced yield and surface terminations, while the intercalant size controlled flake dimensions and quality. To evaluate the electrochemical properties of Nb 2 CT x synthesized using different methods, free-standing films of the MXene were fabricated and tested as electrodes for supercapacitors. The results reveal that synthesis parameters directly determine the electrochemical properties and stability of Nb 2 CT x, providing guidelines for tailoring properties of this MXene for energy storage applications.