Saba Ibrar; Naveed Zafar Ali; Ernest O. Ojegu; Ogo B. Odia; Imosobomeh L. Ikhioya; Ishaq Ahmad
Abstract
Zeolitic imidazolate frameworks (ZIF-8 and ZIF-67) were synthesized for energy storage by utilizing cobalt (II) nitrate hexahydrate, zinc nitrate hexahydrate, and 2-methyl imidazole. ...
Read More
Zeolitic imidazolate frameworks (ZIF-8 and ZIF-67) were synthesized for energy storage by utilizing cobalt (II) nitrate hexahydrate, zinc nitrate hexahydrate, and 2-methyl imidazole. The redox peaks in the CV plots showed the existence of faradaic processes. The specific capacitance of ZIF-8 and ZIF-67 reduces with an increase in scan rate. ZIF-8 and ZIF-67 have estimated specific capacitances of 625, 312, 208, 156, and 125 F/g and 932, 468, 312, 234, and 187 F/g at scan rates of 10 to 50 mV/s. ZIF-8 and ZIF-67 have electrolyte resistances of 1.25 and 1.15 Ω, respectively, with active electrode resistances of 0.03 and 0.02 Ω. Great capacitive performance was indicated by the low charge transfer resistance seen in the Nyquist plots. Both ZIF-8 and ZIF-67 have estimated specific capacitances of 276.91 F/g according to the GCD tests. ZIF-8 and ZIF-67 had an energy density of 7999.89 when the current density was 2.0 A/g. ZIF-8 and ZIF-67 nanocrystals differ in their XRD patterns, as the structure of ZIF-8 remains intact. The nanoparticles exhibit high crystallinity, as evidenced by the distinct peaks observed, particularly the sharp (001) peak at 7.4o. The high-pitched and defined peak at the 2θ position of 7.6° confirmed the crystalline nature of synthesized ZIF-67. The (011) crystal plane was identified as the source of the intense peak at 2θ position 7.6°. The bandgap value of ZIF-67 is 3.27 eV, in contrast to ZIF-8 which has a value of 3.0 eV.
