Density functional calculations of organic pollutants adsorbed on Hittorf's violet phosphorene

Hittorf's violet phosphorene with large specific surface area and high hole mobility is a potential candidate for gas sensing. Here, a case about adsorption behavior of organic chemicals on violet phosphorene has been systematically studied based on density functional theory. From our results, all seven considered organic chemicals (benzoapyrene, benzene, methylbenzene, formaldehyde, m-xylene, o-xylene and p-xylene) on violet phosphorene show molecular adsorption with exothermic process. Among them, the adsorption of benzopyrene with -0.881 eV adsorption energy is most conducive for complete adsorption-desorption cycles, which is an essential feature of reversible gas sensors. Small amounts of charge transfer indicate that the adsorption mechanism is mainly van der Waals type interaction. In particular, further work function and electronic structure analysis indicates that the electrical conductivity changes significantly after benzoapyrene exposure. That makes it possible to transmit gas sensing signals using electrical strategy. We also found that violet phosphorene multi-layer maintains consistent benzoapyrene adsorption performance with its monolayer, which is conducive to practical application. Our simulations could provide theoretical basis for the exploration of two-dimensional organics sensing materials.