Identifying the Atomic Layer Stacking of Mo₂C MXene by Probe Molecule Adsorption

Area of Science:

• Materials Science
• Surface Science
• Computational Chemistry

Background:

• Two-dimensional (2D) MXene materials are a novel class of compounds with diverse applications.
• Understanding the atomic structure of MXenes is crucial for tailoring their properties.
• The influence of atomic stacking on MXene properties is not fully understood.

Purpose of the Study:

• To investigate the impact of atomic stacking on the adsorption properties of MXene materials.
• To determine if adsorption characteristics can serve as an indicator of atomic stacking.
• To explore the case of Molybdenum Carbide (Mo2C) MXene with ABC and ABA stacking.

Main Methods:

• Utilizing density functional theory (DFT) calculations.
• Simulating the adsorption of small gas molecules (CO, CO2, H2O) on different Mo2C MXene polymorphs.
• Analyzing the vibrational spectra of adsorbed molecules.

Main Results:

• Significant differences in adsorption properties were observed between ABC and ABA stacked Mo2C MXene.
• Specific vibrational modes, including asymmetric and symmetric stretching of CO2 and CO stretching, clearly distinguish between the two stacking types.
• These spectral features offer a potential experimental method for identifying atomic stacking.

Conclusions:

• Atomic stacking in MXenes demonstrably affects their adsorption behavior.
• Adsorption spectroscopy can be employed to discern the atomic stacking of Mo2C MXene.
• The findings are expected to be applicable to other MXene materials, aiding in structural characterization.