Modulating the Electronic Properties and Magnetism of Bilayer Phosphorene with Small Gas Molecules Adsorbing

First-principles calculations based on the density functional theory have been performed to investigate the physisorption of small gas molecules, including CO, H2, H2O, NH3, NO, NO2, and O2, on the surface of bilayer phosphorene. The calculated results show that (1) CO, NH3, NO, and O2 molecules act as charge donors, whereas H2O, H2, and NO2 molecules serve as charge acceptors. (2) The interaction between O2 molecule and bilayer phosphorene is strongest among all the researched gas molecules.(3) The physisorption of gas molecules on bilayer phosphorene produces prominent charge transfer, which not only makes phosphorene a promising candidate as a gas sensor, but also provides a valid approach to changing the polarity of phosphorene. (4) The band structure of phosphorene is also modulated by decorating with gas molecules, the NO, O2, and NO2 adsorbed bilayer phosphorene system exhibits magnetism, and NO (O2)-adsorbed phosphorene is a typical n(p)-type semiconductor. (5) In addition, the band gap of CO/H2O adsorbed bilayer phosphorene decreases by exerting increasing external electric fields, which suggests that applying an external electric field would be an effective way to tune the electronic properties of phosphorene and broaden the way to the application of phosphorene in nanoelectronic devices.