3D high-positive-potential spatial strategy enhanced the performance of U66N-FT/COF composites for synergistic adsorption of toluene and formaldehyde: An experimental and theoretical study

Addressing the significant technical hurdle of efficiently capturing mixed-component volatile organic compounds (VOCs) in real-world environments is indispensable. An innovative synthesis strategy for three-dimensional high positive potential (3D-HPP) has been proposed to develop MOF composites (U66N-FT/COF) for the synergistic adsorption of toluene and formaldehyde (FA). Structural and density functional theory (DFT) simulation analyses revealed that the thiophene, amide, and amino sites in U66N-FT/COF synergistically captured FA and toluene. This phenomenon of VOCs capture occurred through π-π conjugation and electrostatic interactions, significantly reducing the competitive adsorption effect among VOCs molecules. Interestingly, the preferential adsorption of FA molecules created secondary adsorption sites for toluene molecules, thereby augmenting the adsorption capacity of toluene by 47.2 % through the dynamic and synergistic mechanism of “Adsorption-Induced-Resorption”. Furthermore, the COF unit in U66N-FT/COF acted as a hydrophobic barrier, significantly impeding the diffusion of H 2 O molecules in the pores and thus effectively weakening the competitive adsorption of H 2 O to VOCs. The experimental findings implied that the U66N-FT/COF composites possessed a remarkable synergistic adsorption activity with a total adsorption capacity of 2.15 mmol/g and a synergistic adsorption coefficient α of 1.11 for the mixed-component VOCs. This study provides an important technical approach and theoretical guidance for addressing the synergistic treatment of multicomponent VOCs in practical scenarios.