Selective sensing properties and enhanced ferromagnetism in CrI3 monolayer via gas adsorption

Recent fabrication of chromium triiodide (CrI3) monolayers has raised potential prospects of developing two-dimensional (2D) ferromagnetic materials for spintronic device applications. The low Curie temperature has stimulated further interest for improving the ferromagnetic stability of CrI3 monolayer. Here, based on density functional theory calculations, we investigated the adsorption energy, charge transfer, electronic and magnetic properties of gases (CO, CO2, N-2, NH3, NO, NO2, O-2, and SO2) adsorption on the CrI3 monolayer. It is found that CrI3 is sensitive to the NH3, NO, and NO2 adsorption due to the high adsorption energy and large charge transfer. The electrical transport results show that the conductivity of CrI3 monolayer is significantly reduced with the adsorption of N-based gases, suggesting that CrI3 exhibits superior sensitivity and selectivity toward N-based gases. In addition, the ferromagnetic stability and Curie temperature (T (C)) of CrI3 monolayer can be effectively enhanced by the adsorption of magnetic gases (NO, NO2, O-2). This work not only demonstrates that CrI3 monolayer can be used as a promising candidate for gas sensing, but also brings further interest to tune the electronic and magnetic properties of 2D ferromagnetic materials via gas adsorption.