Tailoring Janus In₂SeTe monolayers with Al doping: a computational study for NO _x sensing applications

Area of Science:

• Materials Science
• Environmental Science
• Nanotechnology

Background:

• Anthropogenic emissions necessitate advanced gas sensors with high sensitivity and selectivity.
• Janus In2SeTe monolayers are investigated as potential multifunctional gas sensing platforms.

Purpose of the Study:

• To perform a first-principles study on pristine and aluminum-doped Janus In2SeTe monolayers for gas sensing.
• To analyze the adsorption behavior of common pollutants (CO, NH3, CO2, CH4, NO, NO2) and their impact on material properties.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to optimize surface geometry.
• Analysis included adsorption energy, charge transfer, Density of States (DOS), Electron Density Difference (EDD), and recovery time.
• Electronic band structure, conductivity, optical absorption, refractive index, and spin-resolved DOS were evaluated.

Main Results:

• Only NO and NO2 exhibited strong chemisorption on Janus In2SeTe, while other gases showed weak physisorption.
• NOx adsorption significantly narrowed the bandgap, leading to dramatic chemiresistive responses.
• Al-doping substantially boosted sensitivity, with optimized doping levels enhancing sensitivity by factors of 1.26 × 10^5 for NO and 51.6 for NO2.
• Gas-specific shifts in optical absorption and refractive index were observed, alongside the generation of a magnetic moment upon NOx adsorption.

Conclusions:

• Al-doped In2SeTe demonstrates excellent sensing capabilities for NOx detection.
• The material enables concurrent optical, chemiresistive, and magnetic transduction for environmental monitoring.
• Faster recovery times support real-time and reusable detection of NOx pollutants.