New Zr (IV) based metal-organic framework comprising a sulfur-containing ligand: Enhancement of CO₂ and H₂ storage capacity

In order for metal-organic frameworks (MOFs) to be used in gas storage applications, enhancement of the gas sorption capacity is one of the most important issues. It is believed that incorporation of strong gas sorption sites in the framework can increase the gas sorption capacity of MOFs. Herein, we report a new MOF comprising a sulfur-containing ligand (Zr-btdc) for incorporation of electronegative heteroatoms as strong gas-binding sites. Interestingly, despite the smaller surface area of Zr-btdc, it showed higher gas (H₂ and CO₂) sorption capacities than a heteroatom-free isostructural framework (UiO-67). It was expected that the incorporation of a sulfur atom on the ligand would have an effect similar to sulfur doping on the pore surface of the framework. Electrostatic potential analysis showed that heteroatom incorporation in the ligand could increase the electronegativity of the framework surface. Therefore, the incorporation of sulfur atoms on MOFs can create a sulfur-doping effect on the framework surface, resulting in the enhancement of the gas sorption capacities.