A Green Selective Water-Etching Approach to MOF@Mesoporous SiO2 Yolk-Shell Nanoreactors with Enhanced Catalytic Stabilities

Despite their open and uniformly distributed active sites, the relatively low stability of coordination bonds in metal-organic frameworks (MOFs) limits their applications in catalytic reactions, especially under harsh environments. Here, we report a design of MOF@ mesoporous SiO2 yolk-shell nanoreactors via a mesoporous silica coating followed by selective water-etching strategy. Different from conventional alkali-or acid-etching methods, water etching of MOF surface presents a green and cost-effective way to form yolk-shell structures. The yolk-shell nanoreactors exhibit higher catalytic stability than bare MOF crystals in CO2 cyclo-addition with product yield remaining unchanged upon three cycles, owing to their permeable mesoporous SiO2 shells, exposed active sites on MOF surfaces, and protective shells. The design concept and synthetic strategy via selective water etching may be used to construct other highly stable MOF-based nanocatalysts, broadening their applications in diverse catalytic reactions.