Computational analysis of GeSn nanosheet for atmospheric gas sensing: A first-principles approach

Abstract

Rising industrial activity releases toxic gases, demanding sensitive trace-level sensors. In this study, the sensing potential of a germanium-tin (GeSn) monolayer is investigated through first-principles density functional theory (DFT) calculations. The adsorption behavior of six hazardous gases, NO, NH₃, CO, CO₂, H₂S, and SO_2, on the GeSn surface was systematically analyzed. The results reveal that while four of the gases adsorb via physisorption, NO and NH₃ exhibit chemisorption, indicating a stronger interaction with the GeSn surface. All the configurations were further examined through Hirshfeld charge analysis, work function variation, density of states (DOS), and recovery time evaluation. Charge transfer analyses show that the intrinsic dipole moments of the GeSn monolayer influence gas adsorption, with SO₂ and CO acting as electron donors. Notably, SO₂ adsorption leads to pronounced changes in both work function and electronic structure, suggesting a significant modulation of the sensor's electrical response. Overall, the findings underscore the potential of the GeSn monolayer as a highly sensitive and selective sensing material, particularly for the detection of SO₂ gas.