In this study, the synthesis of zeolitic imidazole framework (ZIF-8) in water was systematically studied using 6 zinc sources (Zn(OAc)₂, ZnSO₄, Zn(NO₃)₂, ZnCl₂, ZnBr₂, ZnI₂), respectively, under different conditions at room temperature without using any additives. It was found that Zn(OAc)₂ is the best precursor and the resultant ZIF-8 particles have the best quality with rhombic dodecahedron morphology. The concentration of 2-methylimidazole (Hmim), molar ratio Hmim/Zn and water content all have significant impacts on the morphology, particle size, and crystallinity of ZIF-8. Further result analysis reveals that 3 key reactions are involved in the ZIF-8 formation which needs five steps in ZIF-8 structural evolution. This study provides a deep understanding of the crystallization process of ZIF-8 particles in a water-based system.

Due to the high surface area, atomic-level thickness, and abundant exposed active sites, 2D nanomaterials are regarded potential high-performance adsorbents. We review four representative nanomaterials, graphene, MoS ₂ , MXenes, and MOFs, for this application.