Ambient-Stable Two-Dimensional Titanium Carbide (MXene) Enabled by Iodine Etching.

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• MXenes are 2D materials with metallic conductivity and tunable surface chemistry.
• Conventional synthesis uses hazardous hydrofluoric acid (HF), yielding unstable, fluorine-terminated MXenes.
• There is a need for stable, fluorine-free MXene synthesis for advanced applications.

Purpose of the Study:

• To develop a fluoride-free etching method for producing stable 2D MXene (Ti3C2Tx) nanosheets.
• To investigate the properties of MXene synthesized using an iodine-assisted etching route.
• To evaluate the performance of these novel MXene materials as electrodes for supercapacitors.

Main Methods:

• Utilized a fluoride-free etching process involving iodine (I2) to delaminate MAX powders (Ti3AlC2).
• Characterized the resulting 2D MXene (Ti3C2Tx) nanosheets for size, thickness, and surface termination (oxygen-rich groups).
• Fabricated thin films to measure electrical conductivity and tested MXene-based electrodes in supercapacitors.

Main Results:

• Successfully synthesized 2D MXene (Ti3C2Tx) with oxygen-rich terminal groups and intact lattice structure.
• Over 71% of the MXene sheets were thinner than 5 nm, with an average size of 1.8 μm.
• Achieved excellent thin-film conductivity (1250 S/cm) and high gravimetric capacitance (293 F/g) in supercapacitors, outperforming fluoride-etched counterparts.

Conclusions:

• The iodine-assisted etching route offers a facile, sustainable, and fluoride-free pathway for producing highly stable 2D MXene materials.
• Oxygen-terminated MXene sheets demonstrate superior electrochemical performance for supercapacitor applications.
• This method provides a promising alternative for scalable MXene production with enhanced stability and functionality.