Enhancing SO₂ and NO₂ Gas Sensing Using ZnCdO₂‑Based Porous Nanosheets: A DFT Perspective

The exceptional electronic properties, high surface area, and structural versatility of two-dimensional materials make them excellent candidates for gas-sensing applications. In this study, we propose novel biphenylene (b) and graphenylene (g) lattices of ZnCdO₂ and explore their potential for detecting NO₂ and SO₂ gases via density functional theory calculations. The dynamic and thermal stability of b-(g)-ZnCdO₂ monolayers is confirmed through phonon dispersion and ab initio molecular dynamics simulations. Both gases exhibit favorable adsorption on the monolayers, with significant charge transfer and electronic interaction. Notably, SO₂ interaction on g-ZnCdO₂ is characterized by weak chemisorption, supported by moderate adsorption energy, long-range interaction, and clear surface bonding, suggesting reusability under ambient conditions. Gas adsorption also induces substantial modulation in the work function, reinforcing the suitability of these monolayers for work-function-type sensing. In particular, the g-ZnCdO₂+SO₂ system shows an ultrafast recovery time at room temperature, with improved desorption kinetics at elevated temperatures. These insights position b-(g)-ZnCdO₂ monolayers as promising platforms for efficient and reusable toxic gas sensors.