Imparting Dispersibility and Electrochemical Activity to Chlorine-Terminated MXenes via Oxygen Enrichment

Abstract

Chlorine-terminated Ti3C2 MXenes (Cl-MXenes) demonstrate remarkable resistance to water-and oxygen-induced degradation, yet their hydrophobic nature limits compatibility with polar solvents. This is a stark contrast to the hydrophilic, oxygen-terminated MXenes produced through conventional fluoride-based etching. Capitalizing on the labile character of surface chlorine atoms, we developed a solution-based approach to create oxygen-enriched Cl-MXenes (O,Cl-MXenes) through delamination in alkaline dimethyl sulfoxide. This controlled functionalization yields mixed chlorine-oxygen terminations that substantially improve MXene dispersibility in organic solvents. The partial substitution of chlorine with oxygen and hydroxyl groups, particularly at Ti(II) sites, not only enhances dispersion stability and oxidation resistance but also synergistically combines the anodic stability of chlorine terminations with the high capacitive activity of oxygen groups.These results establish that precise co-functionalization with chlorine and oxygen produces MXenes with enhanced solution processability and environmental stability, providing an important materials design strategy for advancing MXene-based technologies.