Effect of different defects on the competitive adsorption of formaldehyde and water on the surface of carbon materials: Density functional theory study

The adsorption of formaldehyde by carbon materials is extremely limited and is also greatly influenced by the competitive adsorption of water. Therefore, it is of great significance to investigate the effect of different defects on the competitive adsorption of formaldehyde and water on the surface of carbon materials, and consequently the targeted modification of carbon materials to promote the adsorption of formaldehyde in air. In this study, multi-scale simulations were conducted to explore the problem of competitive adsorption of water and formaldehyde on the surface of carbon materials by quantum chemistry and molecular dynamics. IGMH, QTAIM, energy decomposition, electron transfer, and so on were used to conduct a comprehensive analysis of the problem of competitive adsorption of water and formaldehyde on the surface of carbon materials. The reasons for the formation of competitive adsorption between water and formaldehyde were firstly clarified, and then the adsorption interactions of different oxygen-containing functional groups on formaldehyde and water were investigated separately, which were found that the competitive adsorption of water and formaldehyde molecules by different types of oxygen-containing functional groups caused different results. And the introduction of intrinsic defects can promote the adsorption of formaldehyde in the presence of water competition for adsorption, which can well compensate the inhibitory effect of water on the adsorption of formaldehyde with strong polar functional groups. Finally, the results obtained from simulations were used to guide the modification experiments, and the experimental results were in accord with the simulation results. This study provides a new idea for the preparation of materials for efficient formaldehyde adsorption under certain humidity.