NO ₂ and SO ₂ adsorption and sensing on Janus B ₂ SeTe: unveiling its electronic, optical, and magnetic properties through DFT and COMSOL

In this study, the electronic, optical, and magnetic characteristics of a two-dimensional Janus B₂SeTe monolayer, along with its potential for gas sensing applications, were examined using DFT and COMSOL simulations. The interaction and sensing capabilities of various gas molecules, including CO, CO₂, NH₃, SO₂, H₂S, HCN, CH₄, and NO_2, on the B₂SeTe surface were systematically analyzed. Upon geometric optimization, a substantial enhancement in conductivity was observed, increasing by factors of 3.44 × 10¹³ and 2.44 × 10⁷ upon NO₂ and SO₂ adsorption, respectively. The pristine B₂SeTe monolayer demonstrated remarkable sensitivity and selectivity toward NO₂ and SO₂, with NO₂ showing a notably longer recovery time of 7.2798 × 10^-4 s, indicating strong and stable adsorption. The sensor device exhibited an increased response across a concentration range of 25 ppm to 300 ppm, with higher sensitivity to NO₂ (0.02068 ppm^-1) compared to SO₂ (0.00953 ppm^-1). Furthermore, B₂SeTe displayed optical sensitivity to NO₂, and the observed spin splitting under NO₂ adsorption revealed its magnetic sensing capability. These findings suggest that the Janus B₂SeTe monolayer holds significant promise for future gas sensing applications and environmental monitoring systems.