Structural formation and charge storage mechanisms for intercalated two-dimensional carbides MXenes

Area of Science:

• Materials Science
• Computational Chemistry
• Nanotechnology

Background:

• MXenes are promising 2D materials with diverse applications.
• Experimental characterization of MXene surface structures and formation mechanisms remains controversial.

Purpose of the Study:

• To systematically investigate MXene structures formed by intercalating various atoms.
• To reveal the formation mechanisms of MAX, MXA2, MXTx, and MXTxA'x structures.
• To provide a framework for optimizing MXene structures and compositions.

Main Methods:

• First-principles calculations were employed to study MXene structures.
• Competition and matching mechanisms were introduced to predict MAX phase formation.
• Transformation processes from MAX to MXA2 were correlated with energies and chemical potentials.

Main Results:

• A procedure was developed to determine MXene formation mechanisms and probabilities.
• MXene structure (MXTx) was formulated as a function of experimental conditions and c lattice parameter.
• Ti3C2TxAx' capacity was shown to depend on the c lattice parameter, with potential values ranging from 130.3 to 536.8 mA h g-1.
• Energy storage mechanisms were identified as double-layer capacitance and redox storage.

Conclusions:

• The developed procedure effectively explains experimental results and can optimize MXene structures.
• Tailoring the c lattice parameter is crucial for enhancing MXene energy storage capacity.
• Understanding formation mechanisms enables precise control over MXene properties for advanced applications.