Selective sensing properties and enhanced ferromagnetism in CrI 3 monolayer via gas adsorption.

Recent fabrication of chromium triiodide (CrI 3 ) 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 CrI 3 monolayer. Here, based on density functional theory calculations, we investigated the adsorption energy, charge transfer, electronic and magnetic properties of gases (CO, CO 2 , N 2 , NH 3 , NO, NO 2 , O 2 , and SO 2 ) adsorption on the CrI 3 monolayer. It is found that CrI 3 is sensitive to the NH 3 , NO, and NO 2 adsorption due to the high adsorption energy and large charge transfer. The electrical transport results show that the conductivity of CrI 3 monolayer is significantly reduced with the adsorption of N-based gases, suggesting that CrI 3 exhibits superior sensitivity and selectivity toward N-based gases. In addition, the ferromagnetic stability and Curie temperature ( T C ) of CrI 3 monolayer can be effectively enhanced by the adsorption of magnetic gases (NO, NO 2 , O 2 ). This work not only demonstrates that CrI 3 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.