Controlled Construction of Supported Cu⁺ Sites and Their Stabilization in MIL-100(Fe): Efficient Adsorbents for Benzothiophene Capture

Cu⁺-containing materials have drawn much attention in various applications because they are versatile, nontoxic, and low-cost. However, the difficulty of selective reduction and the poor stability of Cu⁺ species are now pretty much the agendas. Here, controlled construction of supported Cu⁺ sites in MIL-100(Fe) was realized under mild conditions (200 °C, 5 h) via a vapor-reduction strategy (VRS). Remarkably, the yield of Cu⁺ reaches 100%, which is quite higher than the traditional high-temperature autoreduction method with a yield less than 50% even at 700 °C for 12 h. More importantly, during the treatment via VRS some Fe³⁺ in MIL-100(Fe) are reduced to Fe²⁺, which prevent the frequently happened oxidation of Cu⁺ due to the higher oxidation potential of Fe²⁺. These properties make Cu⁺/MIL-100(Fe) efficient in the capture of typical aromatic sulfur, benzothiophene, with regard to both adsorption capacity and stability. To our knowledge, the stabilization of Cu⁺ using the oxidation tendency of supports is achieved for the first time, which may offer a new idea to utilize active sites with weak stability.