Adsorption studies of air pollutants on α-SbP with density functional theory

The sensing behaviors of monolayer antimonide phosphorus (SbP) for air pollutants (CO, CO2, H2S, SO2 NO, NO2 and NH3) are studied by using the density functional theory. In this paper, we computed the adsorption energy, charge transfer, adsorption distance, band gap, electronic structure and recovery time of gas molecules on monolayer SbP. The calculated results indicate that monolayer SbP is sensitive to SO2, NO and NO2 molecules via strong physical interaction. Through the analysis of charge transfer, it could be seen that there were more charges transfer of NO (0.549e), NO2 (- 0.366e) and SO2 (- 0.263e) gas molecules than other gases. When SO2, NO and NO2 gas molecules are adsorbed on the monolayer SbP, the band structure was reduced apparently. In particular, for NO2 adsorption, impurity bands pass through the Fermi surface, making the system appear semimetallic properties. Furthermore, the adsorption of NO and NO2 can cause obvious deviation in the DOS. On further analysis, we knew that these changes were mainly due to the orbital hybridization between the p orbitals of N, O and S atoms and the p orbitals of Sb and P atoms. Theoretical studies show that monolayer SbP may be a potential gas sensing material for SO2, NO and NO2 gas molecules.