Monolayer Ti₂CO₂: A Promising Candidate for NH₃ Sensor or Capturer with High Sensitivity and Selectivity

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• MXenes, particularly Ti2C, are emerging 2D materials with diverse applications.
• Monolayer Ti2CO2 exhibits unique electronic and surface properties.
• The development of novel gas sensors and capture materials is crucial for environmental monitoring and industrial safety.

Purpose of the Study:

• To investigate the adsorption behavior of various gas molecules on monolayer Ti2CO2.
• To evaluate the potential of Ti2CO2 as a gas sensor and capturer for ammonia (NH3).
• To explore the influence of strain on NH3 adsorption and capture reversibility.

Main Methods:

• First-principles simulations were employed to study gas adsorption.
• Density Functional Theory (DFT) calculations were performed.
• Nonequilibrium Green's function (NEGF) method was used to analyze current-voltage (I-V) characteristics.

Main Results:

• Only ammonia (NH3) exhibited chemisorption on Ti2CO2 with significant charge transfer.
• NH3 adsorption dramatically altered the I-V relation of Ti2CO2, indicating sensing capabilities.
• Applied strain enhanced NH3 adsorption, while other gases showed weak interaction, suggesting selective capture.
• NH3 desorption was achieved by releasing strain, confirming reversible capture.

Conclusions:

• Monolayer Ti2CO2 is a promising candidate for highly selective and sensitive ammonia (NH3) gas sensors.
• Ti2CO2 demonstrates potential as a reversible capturer for NH3, especially under applied strain.
• This research expands the application scope of monolayer Ti2CO2 beyond battery materials to gas sensing and capture.