Alkali treated Ti3C2Tx MXenes and their dye adsorption performance

To modify the adsorption performance of Ti3C2Tx MXene, we report a facile approach to expand the interlayer spacing of Ti3C2Tx and to tune its surface functional groups by hot alkaline solution treatment. In the treatment, the interlayer spacing of Ti3C2Tx MXene is increased by up to 29% by LiOH, and the surface functional groups are tuned by converting -F to -OH. Among the MXenes, LiOH-Ti3C2Tx and NaOH-Ti3C2Tx can faster adsorb methylene blue (MB) than other MXene adsorbents; NaOH-Ti3C2Tx possesses the highest adsorption capacity (189 mg/g) for MB, which can be ascribed to the cooperation of surface adsorption and intercalation adsorption. The experimental data suggest that the enhanced adsorption toward cationic dyes can be best described by a Langmuir isotherm.