Hierarchical Pore Development of ZIF-8 MOF by Simple Salt-Assisted Mechanosynthesis

An efficient and simple mechanosynthesis was proposed to synthesize zeolitic imidazolate-based metal organic framework ZIF-8 with hierarchical superstructure. The synthesis strategy is based on a concept that only uses precursor powders for ease of handling in the solid–solid mechanochemical reaction. The solvent-free conversion of ZnO to ZIF-8 could be accelerated by an addition of zinc acetate dihydrate as both a Zn source and a catalyst. The acid dissolution of ZnO and complex forming reaction between ionized Zn and 2-methylimidazole were facilitated by the hydrated water and acetic acid generated sequentially from zinc acetate dihydrate during the reaction process. The mechanochemically synthesized ZIF-8 with trimodal hierarchical porous structure exhibited excellent adsorption rate capabilities. The large-scale rapid production and enhanced adsorption performances make this salt-assisted mechanosynthesis a very promising candidate for the industrial application and shaping of metal organic frameworks.