Adsorption of CO2 and CO gas on impurity-decorated phosphorenes: A first-principles study

Abstract

Recently, a new category of layered direct-bandgap semiconductor, phosphorene, with high-mobility transport anisotropy and linear dichroism, has been theoretically discovered and successfully fabricated by micromechanical exfoliation methods. It has been theoretically reported that pristine phosphorene is insensitive to some gas molecules, such as CO and CO 2 . In this work, we have performed a systemically first-principle study on the adsorption behaviors of different gases (CO 2 and CO) over impurity-docorated phosphorenes to its potential as gas sensors. The adsorption energy (E a ), adsorption distance (d) and Mulliken charge (Q) of different gas molecules adsorbed on the different phosphorenes are calculated. Our results reveal that silicon-doped phosphorenes significant improve the adsorption capacity of pristine phosphorene, while a negative effect we observed after the introduction of S. In order to get further insights into the mechanism of interaction between the gas molecules and phosphorenes, we also calculate difference charge densities for CO gas over Si- and S-doped phosphorenes, the charges are remarkably redistributed after adsorbing CO on the Si-doped phosphorene which further indicating the strong interaction between CO gas and Si-doped phosphorene. Such evident charge redistribution is absent for the CO gas on S-doped phosphorene. Furthermore, the partial charge densities indicate that the presence of orbital hybridization between CO gas and Si-doped phosphorene. Therefore, we suggest that our findings pave a new way for fabricating gas sensors based on silicon-doped phosphorene.