Room-Temperature Synthesis of ZIF-8: The Coexistence of ZnO Nanoneedles

摘要

Zeolite imidazolate frameworks (ZIFs) are novel type of microporous crystalline materials displaying unique and highly desirable properties from both zeolites and metal organic frameworks, such as remarkable high surface areas, crystallinity, unimodal micropores, as well as thermal and chemical stability. Typically, ZIFs are composed of Zn and Co atoms linked through N atoms by ditopic imidazolate (Im) or functionalized 1m links to form neutral frameworks and to provide tunable nanosized pores formed by four-, six-, eight-, and twelve-membered ring ZnN4, and CoN4 tetrahedras. Although the great potential of ZIFs as novel functional materials has been demonstrated recently in diverse fields, including gas separations, sensing, and catalysis, to the best of our knowledge, only few reports, including our recent work, a has been published on the mechanistic aspects of ZIFs formation. A basic understanding on the formation mechanisms of zeolitic imidazolate frameworks is important to rationally develop materials with tailored structural, compositional, and morphological properties. Herein, we followed the crystallization-time dependence of a representative zeolitic imidazolate framework, ZIF-8 which has large pores of 11.6 A accessible through small apertures of 3.4 A. Interestingly, when zinc carbonate basic was used as the metal source, the coexistance of ZIF-8 and ZnO nanoneedles was observed.