Facile synthesis of benzimidazole based mono- and bimetallic zeolitic imidazole frameworks for enhanced CO2 capture performance

Utilization of Zeolite imidazole frameworks (ZIFs) based membrane for Efficient CO2 capture is one of the most significant and advantageous methods to reduce the greenhouse gas quantity in the atmosphere. Here we report a simple room temperature synthesis of robust monometallic ZIF-7, ZIF-9 and bimetallic Zn2+ and Co2+ containing ZIFs to achieve five porous meterials, Zn100−xCox-ZIF (X = 0, 25, 50, 75 and 100). All the synthesized ZIFs are characterized through powder X-ray diffraction, thermogravimetric analysis (TGA), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) to examine the phase, texture, morphology, chemical state and surface area. The presence of metal in a specific ratio was examined through the Energy Dispersive X-ray Spectrometer (EDS). Incorporation of Cobalt into Zn containing ZIFs not only increases their thermal stability but also enhances their photophysical properties, thereby decreasing the optical band gap. Furthermore, bimetallic ZIFs exhibited higher specific surface area and CO2 uptake capacity than their parents monometallic counterparts. Specific surface area and CO2 uptake capacity of mono/ bimetallic ZIFs were studied at 298 K. The CO2 uptake of 1.83 cm3/g, 4.76 cm3/g, 6.26 cm3/g, 9.62 cm3/g, and 16.62 cm3/g for ZIF-7, ZIF-9, Zn100−xCox-ZIF (X = 25, 50 and 75), respectively, are obtained.