Mechanochemical synthesis of bimetallic CoZn-ZIFs with sodalite structure

An efficient and simple methodology was proposed to synthesize bimetallic Co–Zn based zeolitic imidazolate frameworks (CoZn-ZIFs; CoxZn(1−x)(2-methylimidazole)2) with sodalite topology. The synthesis strategy is based on a solventless mechanochemical reaction using only powder raw material, zinc oxide, cobalt acetate, and 2-methylimidazole, for ease of handling and large-scale production. The solventless conversion of ZnO into CoZn-ZIF could be promoted by adding cobalt acetate as both Co source and catalyst. A feature of the acetate-assisted mechanosynthesis is that CoZn-ZIF particles are tens of micrometers in size and hierarchically structured. Co and Zn elements are homogeneously dispersed in the framework. Tuning the additive amount of cobalt acetate could vary the Co/Zn ratio of CoZn-ZIF particles. Compared with Zn-ZIF prepared by adding zinc acetate, CoZn-ZIFs exhibited enhanced CO2 uptake. The enhancement of 35% for CO2 uptake capacity at 298 K and 100 kPa was displayed by Co0.9Zn0.1-ZIF as compared to Zn-ZIF.