Fabrication of Cu⁺ sites in confined spaces for adsorptive desulfurization by series connection double-solvent strategy

Cu⁺-containing materials have shown various application prospects especially in adsorption and catalysis, because they are versatile, non-toxic and low cost. To date, developing a mild and controllable approach for the fabrication of Cu⁺ sites has remained a pronounced challenge. Herein, we report a series connection double-solvent strategy (SCDS) for fabricating Cu⁺ sites within MIL-101(Cr), a typical metal–organic framework. By employing the SCDS in which vitamin C is chosen as the environmentally benign reducing agent, Cu²⁺ was incorporated in the pores and then transformed to Cu⁺ in the confined spaces. Compared to the conventional high-temperature autoreduction method conducted under harsh environment (700 °C for 12 h) with a low Cu⁺ yield (less than 50%), SCDS can selectively reduce Cu²⁺ to Cu⁺ at room temperature without generating any Cu⁰. The resulting Cu⁺ modified MIL-101(Cr) exhibits good desulfurization performance in view of both uptake and recyclability.