Comprehensive synthesis of Ti₃C₂T_x from MAX phase to MXene

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• MXenes are a class of 2D materials with exceptional optoelectronic, biological, mechanical, and chemical properties.
• Existing synthesis methods yield variations in MXene flake size, defects, and surface chemistry, impacting material performance.
• Titanium carbide (Ti3C2Tx) is a prominent and widely utilized MXene.

Purpose of the Study:

• To provide a detailed, standardized protocol for synthesizing Ti3C2Tx MXene from a Ti3AlC2 MAX phase precursor.
• To offer guidance for researchers new to MXene synthesis, particularly using the hydrofluoric acid/HCl etching method.
• To enable the adaptation of this protocol for synthesizing other MXene materials.

Main Methods:

• Synthesis of the Ti3AlC2 MAX phase precursor.
• Wet chemical etching of the MAX phase using hydrofluoric acid (HF) and hydrochloric acid (HCl) to produce multilayer Ti3C2Tx.
• Delamination of multilayer Ti3C2Tx into single-layer flakes using three distinct methods: LiCl, tertiary amines (tetramethylammonium hydroxide/tetrabutylammonium hydroxide), or dimethyl sulfoxide (DMSO).

Main Results:

• The protocol yields Ti3C2Tx MXene with a low concentration of defects and high electrical conductivity.
• The synthesis process involves three main stages: MAX phase synthesis (approx. 1 week), etching (2 days), and delamination (2 days).
• Successful execution requires experience with hydrofluoric acid, wet chemistry, centrifugation, and characterization techniques like X-ray diffraction and particle size analysis.

Conclusions:

• This standardized protocol offers a reliable method for producing high-quality Ti3C2Tx MXene.
• The described wet chemical etching and delamination procedures are crucial for obtaining defect-minimized, conductive MXene flakes.
• While alternative methods exist, this protocol focuses on the widely applicable and effective HF/HCl etching approach for Ti3C2Tx synthesis.