Adsorption mechanisms of different toxic molecular gases on intrinsic CN and Ti-CN monolayer: a DFT study.

Recently, the excessive emission of chemical toxic gases such as nitrogen trifluoride (NF), ammonia (NH), phosgene (COCL), and benzene (CH) has caused serious environmental problems. Adsorption of these chemical toxic gas molecules is a promising method to reduce environmental pollution. In this work, density functional theory (DFT) calculations are used to investigate the adsorption properties of these chemical toxic molecules on intrinsic CN and Ti-CN monolayer. The results show that NF, NH, CH, and COCL can all be adsorbed to the intrinsic CN monolayer with weak adsorption energy, while the adsorption properties of these gas molecules were greatly improved after doping Ti atom. The adsorption energy of NH, CH, COCL, and NF increased from - 0.585, - 0.432, - 0.633, and - 0.362 eV to - 2.214, - 1.699, - 1.822, and - 0.799 eV, respectively, which increased by 2 ~ 4 times compared with that before doping. Besides, the results of the electron distribution, work function, the total density of states (TDOS), and the partial density of states (PDOS) analysis indicate that the doped Ti atom can be used as a bridge to connect the adsorbed molecules with the CN monolayer, strengthen their interaction, and significantly improve the adsorption capacity. Therefore, Ti-doped CN (Ti-CN) monolayer is a promising adsorbent for the enrichment and utilization of harmful gases.