Surface free electrons endow 2D Alkali metal nitrides with extraordinary adsorption on volatile organic compounds

Volatile organic compounds (VOCs) are a major cause of leukemia, carcinoma, and other diseases. However, removal technologies for VOCs cannot cope with the grim situation of VOC pollution. Two-dimensional (2D) alkali metal nitrides Ca ₂ N, Sr ₂ N, and Ba ₂ N have great potential as a new adsorption material, and their application as a VOCs detector has not reported. Here, we study the sensing performance of Ca ₂ N, Sr ₂ N, and Ba ₂ N on benzene, styrene, xylene, methylbenzene, ethylbenzene, butyl acetate, methanal, and n-undecane. We find that Ca ₂ N, Sr ₂ N, and Ba ₂ N have outstanding adsorption capabilities for VOCs. This strong adsorption is attributed to the free-electron layer on their surface. When the isosurfaces are equal, there are more free electrons on the surface of Ca2N, followed by Sr2N, and finally Ba2N. Moreover, electric fields could effectively improve their adsorption performance. The perfect match of the electronic properties of VOCs with those of Ca2N, Sr2N, and Ba2N contributes to this extraordinary adsorption capability. Therefore, this study will lead to a new round of technological innovation in VOCs adsorption technology based on 2D alkali metal nitrides.