Effect of Synthesis Conditions on the Morphology, Stability and Electrochemical Properties of Nb₂CT_x MXenes

MXenes have gained significant attention in recent years for their unique properties and potential applications. Among several compositions of MXenes synthesized so far, Niobium carbide (Nb₂CT_x) MXene has shown promise for use in batteries, supercapacitors, photocatalysts, and fuel cells. However, despite many studies on the properties of this material, the effect of the synthesis process on the morphology, stability, and electrochemical properties of single-layer Nb₂CT_x MXenes, has not been extensively studied before. In this study, we have explored various etching and delamination processes for Nb₂CT_x and propose an improved synthesis process. Etching of the Nb₂AlC MAX phase was performed in two different etchants and followed by delamination with TBAOH or TMAOH. Our results show that the synthesis yield is highly dependent on the composition of the etchant. Also, the size and quality of the produced MXene can be tuned by adjusting the etching and delamination conditions. To evaluate the electrochemical properties of Nb₂CT_x synthesized using different methods, free-standing films of the MXene were fabricated and tested as supercapacitor electrodes. These studies also showed the dependence of the electrochemical properties and stability of produced MXenes on the synthesis condition.