Biaxial Strain Engineering for High-Performance Monolayer GeSe Sensors toward Nitrogen-Containing Toxic Gases

Area of Science:

• Materials Science
• Surface Science
• Computational Chemistry

Background:

• Strain engineering is crucial for tuning the properties of 2D materials like Germanium Selenide (GeSe).
• Understanding strain's effect on GeSe's gas-sensing selectivity for nitrogen-containing pollutants is limited.

Purpose of the Study:

• To investigate the strain-governed sensing mechanism of monolayer GeSe for nitrogen oxides (NO, NO2) and ammonia (NH3).
• To explore how biaxial strain enhances selectivity and differentiates these gases.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Non-equilibrium Green's function (NEGF) method for electronic transport analysis.
• Simulations of gas adsorption and electronic response under varying strain conditions.

Main Results:

• Pristine GeSe shows selectivity for NO2, with weak interactions for NO and NH3.
• A 4% biaxial compressive strain induces distinct responses: NO2 causes a semiconductor-to-metal transition, NO leads to spin-polarized currents (100% filtering), and NH3 shows minimal perturbation.
• Strain enhances gas adsorption, modifies the bandgap, and alters transport pathways, leading to rapid desorption and recyclability.

Conclusions:

• Biaxial strain engineering activates unique electronic responses (metallicity, spin polarization, inertness) in GeSe.
• Strained GeSe acts as a highly selective gas sensor for differentiating chemically similar nitrogen species.
• This work establishes strained GeSe as a tunable platform for next-generation gas sensing applications.