Zeolitic-Imidazolate Frameworks (ZIFs), in which tetrahedrally-coordinated metal ions (Co, Zn, Cu et al.) are linked with N atoms of imidazolate linkers, are a class of Metal-Organic Frameworks (MOFs). Due to their uniform pore size, ultrahigh surface area and good chemical stability, ZIFs are regarded as promising materials for gas storage, catalysis, drug delivery and many applications. Also, it has been demonstrated that bimetallic Zn-Co based ZIFs have better gas sorption performances than homometallic ZIF, because of their larger surface area and higher porosities. In this work, hybrid Zn/Co-ZIF and core-shelled ZIF-67@ZIF-8, with rhombic dodecahedral shape and uniform particle size, were successfully synthesized at room temperature. The surface area of Zn/Co-ZIF and ZIF-67@ZIF-8 (1904 and 2030 m2/g respectively) is found to be larger than most of the reported Zn-ZIF. The as-prepared ZIFs have enhance H2 and CO2 adsorption capabilities as well. Furthermore, void space enables ZIFs to have the abilities of encapsulating other guest spices and improving the diffusion of molecules. However, precise control of the hollow structure using a mild and efficient method is still challenging. Thus, a facile acid etching process was further introduced to obtain hollow interior with continuous and unbroken shell. Yolk-shelled to single-shelled structure is tunable with different etching time. Hollow Zn/Co-ZIF and ZIF-67@ZIF-8 are expected to have large surface area and expanded functionality, which are promising in gas storage and gas phase catalysis.

Room-temperature synthesis of Zn–Co–based zeolitic imidazolate frameworks with hollow structure

2019 Fall National Meeting

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