Taming the transition between ZIF-L–(Zn, Co) and ZIF-(8, 67) using a multi-inlet vortex mixer (MIVM)

Abstract

Zeolitic imidazolate frameworks (ZIFs) have attracted extensive attention due to their high porosity, exceptional surface area and remarkable thermal and chemical stability leading to a distinguished performance in various fields like catalysis, gas separation, carbon dioxide capture, and drug delivery. Some major challenges in the ZIF research are concerned with the synthesis of high-quality ZIF-(8, 67) crystals in an aqueous medium with reduced organic ligand consumption and controlled particle size. Herein, we report the controlled transition from ZIF-L–(Zn, Co) to ZIF-(8, 67) and the controlled particle size synthesis of ZIF-(8, 67), and the composition of their mixed metal derivatives in a multi-inlet vortex mixer (MIVM). The method uses precursor solutions in four controlled flow syringes that feed them into the MIVM at various flow rates. The collected ZIF particles are then fully characterized, and their composition is determined. We show that this synthesis technique is rapid and provides superior control over the transition from ZIF-L to ZIF-(8, 67) via the flow rates of the initial ZIF precursors and their molar ratio. Moreover, using the MIVM, we can synthesize ZIF-8 nanoparticles with a minimum mean particle size of 76 nm ± 2 nm compared to a mean particle size of 97 nm ± 20 nm obtained by the traditional batch technique. The controlled doping of ZIF-8 by cobalt is also achieved.