Achieving Macroscopic V₄C₃T MXene by Selectively Etching Al from V₄AlC₃ Single Crystals

Area of Science:

• Materials Science
• Solid State Chemistry
• Nanotechnology

Background:

• MAX phases are a unique class of ternary carbides and nitrides with promising properties.
• V4AlC3 is a less-explored member of the MAX phase family.
• Understanding the fundamental properties of V4AlC3 is crucial for its potential applications.

Purpose of the Study:

• To synthesize and characterize V4AlC3 single crystals.
• To investigate the oxidation behavior and corrosion resistance of V4AlC3.
• To explore the potential for V4AlC3 as a precursor for MXene synthesis.

Main Methods:

• High-temperature flux method for crystal growth.
• X-ray diffraction (XRD), FE-SEM, and EDX for material characterization.
• Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) for oxidation studies.
• Raman spectroscopy (RS) for structural analysis.
• Corrosion tests in various acids and alkalis.

Main Results:

• Successfully grew hexagon-like V4AlC3 single crystals.
• Reported the first-order Raman spectra of V4AlC3 experimentally and theoretically.
• Clarified the oxidation mechanism of V4AlC3 between 300 and 1473 K.
• Determined V4AlC3 stability in HCl, H2SO4, and NaOH, but instability in KOH and HNO3.
• Demonstrated the selective etching of Al layers by HF to form V4C3Tx MXene.

Conclusions:

• V4AlC3 single crystals exhibit distinct oxidation and corrosion behaviors.
• Hydrofluoric acid selectively etches Al layers, yielding V4C3Tx MXene.
• This method provides a route to macroscopic MXenes for electronic and photonic applications.