Gas-Sensing Properties of CO2, CO, SO2, and H2S on an SbP Monolayer Based on Density Functional Theory

The sensing and detection of toxic and hazardous gases represents a critical technology in urgent need of development. Herein, density functional theory is employed to explore the adsorption characteristics and electronic response of CO2, CO, SO2, and H2S on an SbP monolayer. The four molecules are all weakly adsorbed on the surface with adsorption energies between −0.097 and −0.242 eV. In particular, SO2 shows the strongest interaction and accepts 0.096 e from the SbP monolayer. After adsorbing the gas molecules, the SbP monolayer maintains its semiconductor properties, but its energy bands and density of states are modulated to varying degrees. SO2 reduces the bandgap of the SbP monolayer from 1.71 eV to 1.60 eV and has the most pronounced effect on the electronic states near the Fermi level. The sensitivity shows that the response of the SbP monolayer to SO2 at 300 K reaches 5.913, and it remains consistently higher than that to CO2, CO, and H2S within the temperature range of 300–500 K. SO2 adsorption also induces a change in work function of 0.567 eV, while its recovery time remains on a relatively short time scale. The above results suggest that among the four gases investigated, SO2 has the most significant modulation effect on the electronic properties of the SbP monolayer and exhibits good theoretical desorption capability. Therefore, the SbP monolayer can be considered as a robust candidate gas-sensing material for SO2 detection.