Stabilizing Cu^I in MIL-101(Cr) by introducing long-chain alkane for adsorptive desulfurization

Cu^I-functionalized materials are highly promising for diverse applications. Unfortunately, the poor oxidation resistance of Cu^I limits their practical applications. Due to the co-presence of moisture and oxygen, Cu^I is easily oxidized to Cu^II, resulting in loss of activity. Herein, we have tailored a superhydrophobic microenvironment to stabilize Cu^I against oxidation by coordinating octadecylphosphonic acid (OPA) onto metal nodes on the surface of metal–organic frameworks. As a proof of concept, MIL-101(Cr) was employed as support to introduce Cu^I active sites, producing Cu^IM. By grafting OPA onto metal nodes on the surface, the original hydrophilic surface turns to be superhydrophobic, which hinders the access of moisture to Cu^I, thus stabilizing Cu^I despite the aerobic conditions. The OPA-grafted material, Cu^IM-OPA, shows constant Cu^I content under the atmosphere for a month, while only 4% Cu^I is retained in Cu^IM after a week. After exposure for a month, Cu^IM-OPA can remove 0.232 mmol/g thiophene, which is evidently superior to Cu^IM (0.015 mmol/g) in spite of the similar initial uptakes. Notably, Cu^IM-OPA shows intriguing adsorptive desulfurization from hydrated fuel without loss in four cycles, whereas only 4% capacity is retained in Cu^IM.