Gas molecular adsorption effects on the electronic and optical properties of monolayer SnP₃

We have investigated the electronic and optical properties of monolayer SnP₃ adsorbed by small gas molecules by using first-principle calculations based on density functional theory. Six initial adsorption sites were selected to explore the most sensitive site to investigate the optimal adsorption positions of CH₄, H₂O, NH₃, NO, NO₂, and SO₂ adsorbed on the monolayer SnP₃. Aiming at the optimal adsorption configurations, the adsorption energy, adsorption distance, and charge densities are computed to investigate the adsorption types. Our results reveal that monolayer SnP₃ is sensitive to NO and SO₂ via strong physical adsorption, and NO₂ via chemical adsorption, thereby forming a new bond between O and P atoms. Analysis of the optical property shows that the adsorption of NO, NO₂, and SO₂ can remarkably influence the dielectric function and adsorption coefficient of monolayer SnP₃. Our theoretical studies indicate that monolayer SnP₃ is a good gas-sensitive material used for NO, NO₂, and SO₂ detection.