Strain-engineered 2D h-BC2N monolayer as a potential gas sensor with exceptional sensitivity and selectivity for NO2 gas detection

Nitrogen-containing gases present notable threats to the human health and the environment, largely attributed to increased toxicity arising from industrial processes. This study assesses the reactivity of strained and unstrained h-BC2N monolayers towards NO2, NH3, and HCN gases using density functional theory and ab-initio molecular dynamics simulations. The monolayer-gas interactions were analyzed by incorporating van der Waals dispersion correction. Biaxial tensile strain was found to reduce the band gap from 2.2 eV (unstrained) to 2.1 eV (4 % strained). NO2 gas adsorption energy notably increases across strain levels from −0.43 eV to −0.68 eV for 0 %–4 % strain, respectively. Conversely, NH3 and HCN show low adsorption energies on both strained and unstrained h-BC2N monolayers. Electronic analyses indicate the heightened sensitivity of NO2 compared to NH3 and HCN, with minimal sensitivity shown towards H2O, CO2, HF, H2, and H2S gases, suggesting high selectivity for NO2. Recovery time increases significantly from 18.98μs to 323 ms with strain levels from 0 % to 4 %, enhancing NO2 adsorption stability. Ab-initio molecular dynamics simulations conducted at 300K validate the stability of both the unstrained and strained BC2N monolayers. The revealed adsorption mechanism highlights the stability, sensitivity, selectivity, and recyclability of strained h-BC2N monolayers for NO2 gas sensing.