Engineering New Defects in MIL-100(Fe) via a Mixed-Ligand Approach To Effect Enhanced Volatile Organic Compound Adsorption Capacity

In the development of metal–organic frameworks (MOFs), expansion of pore size and exploration of facile preparation conditions are considered as two major goals that are rarely realized together. This study develops a facile method for the room-temperature synthesis of hierarchically porous MIL-100(Fe) under HF-free conditions using a mixed-ligand strategy by simultaneously introducing p-benzoquinone and terephthalic acid (TPA). The resulting MIL-100(Fe) products exhibited abundant micropores, large mesopores (∼40 nm) and macropores, and high stability, as revealed by N2 adsorption–desorption isotherms, pore size distributions, scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The synthesis mechanism of hierarchically porous MIL-100(Fe) elucidated that the introduced p-benzoquinone accelerated crystallization, while TPA generated crystal defects. The as-synthesized hierarchically porous MIL-100(Fe) acted as adsorbents with significantly improved performance than conventional MOFs and zeolites used for toluene and p-xylene adsorption. Furthermore, the adsorption behavior of toluene and p-xylene molecules in MIL-100(Fe) was investigated using molecular simulations. This simple and facile mixed-ligand method shows promise for the large-scale and low-cost production of various hierarchically porous MOFs in a wide range of applications.