Adsorption mechanisms of different volatile organic compounds onto pristine C2N and Al-doped C2N monolayer: A DFT investigation

Volatile organic compounds (VOCs) are a class of air pollutants which seriously affect the ecological environment and threaten human health. Adsorption of VOCs is considered as a promising technology for VOCs enriching, separation and utilization. In this work, density functional theory (DFT) calculations are employed to investigate the adsorption properties of typical VOCs molecules onto C2N monolayer and Al-doped C2N system due to the huge specific surface and porous structure of newly-reported holey two-dimensional C2N. The results demonstrate that three typical VOCs: formaldehyde, benzene and trichloroethylene, can be absorbed onto pristine C2N monolayer with weak adsorption energy, while the adsorption ability can be improved with the formation of a strong chemical bond. Especially for the formaldehyde molecule, the best adsorption capacity on the Al-doped C2N surface with adsorption energy of -2.754 eV, nearly 5 times larger than the pristine C2N system. The PDOS analysis and electronic distribution results also show that doped Al atom can act as a bridge to link VOCs molecules with C2N monolayer and strengthen their interaction, which can significantly enhance the adsorption capacity. Therefore, Al doped C2N monolayer is demonstrated to be a promising adsorbent for VOCs enriching and utilization. (C) 2018 Elsevier B.V. All rights reserved.