Trace benzene capture by decoration of structural defects in metal-organic framework materials

Capture of trace benzene is an important and challenging task. Metal-organic framework materials are promising sorbents for a variety of gases, but their limited capacity towards benzene at low concentration remains unresolved. Here, we report the adsorption of trace benzene by decorating a structural defect in MIL-125-defect with single-atom metal centres to afford MIL-125-X (X = Mn, Fe, Co, Ni, Cu, Zn). At 298 K, MIL-125-Zn exhibits a benzene uptake of 7.63 mmol g^-1 at 1.2 mbar and 5.33 mmol g^-1 at 0.12 mbar, and breakthrough experiments confirm the removal of trace benzene (from 5 to <0.5 ppm) from air (up to 111,000 min g^-1), even after exposure to moisture. The binding of benzene to the defect and open Zn(Ⅱ) sites at low pressure have been visualised by diffraction, scattering and spectroscopy. This work highlights the importance of fine-tuning pore chemistry for designing adsorbents for the removal of air pollutants.