Enhanced Water Stability in Zn-Doped Zeolitic Imidazolate Framework-67 (ZIF-67) for CO2 Capture Applications

In this work, the water stability of zeolitic imidazolate framework-67 (ZIF-67) is successfully enhanced by Zn-doping during the crystallization process. Both elemental mapping analysis and X-ray diffraction (XRD) results reveal that Zn element is doped in the ZIF-67's crystals. The thermal stability, surface area and CO2 capacity are not significantly affected by Zn-doping as evidenced by thermogravimetric analysis (TGA) and gas sorption. When exposed to liquid water, the doped ZIF-67 s show better stability in terms of crystal structure, morphology, surface area and CO2 uptake capacity. However, the undoped ZIF-67 crystals collapse and nearly lose their porosity as well as CO2 uptake capacity after the same exposure. This study provides a new approach to enhance the water stability of ZIF-67.