In situ synthesis of a non-toxic cobalt–benzimidazole metal–organic framework decorated reduced graphene oxide composite for asymmetric supercapacitor applications

• Published in: New journal of chemistry 2023-03, Vol.47 (10), p.4832-4844
• Main Authors: Elanthamilan, Elaiyappillai, Ganeshkumar, Arumugam, Wang, Sea-Fue, Rajaram, Rajendran
• Format: Article
• Language: English
• Subjects: Biocompatibility; Cobalt; Electrochemical impedance spectroscopy; Electrode materials; Electrodes; Energy storage; Graphene; Hydrothermal treatment; Metal-organic frameworks; Supercapacitors; Surface area; Synergistic effect; Synthesis; X ray photoelectron spectroscopy; Zeolites
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/D2NJ06209G

In this article, we report an effective synthesis of a cobalt–benzimidazole metal organic framework (Co–Bi m MOF), which belongs to the Zeolitic imidazolate framework-9 (ZIF-9) family, and a cobalt–benzimidazole MOF@reduced graphene oxide (Co–Bi m @rGO) composite through hydrothermal treatment for supercapacitor application. The structural and morphological features of the Co–Bi m MOF and Co–Bi m @rGO composite were confirmed by using various physicochemical techniques such as FT-IR, Raman, XRD, SEM, TEM, BET and XPS analysis. The SEM and BET analysis of the Co–Bi m @rGO composite shows a layer-like structure with abundant pores and a large surface area (543 m 2 g −1 ). The supercapacitive performance of the prepared electrodes was investigated using CV (cyclic voltammetry), GCD (Galvanostatic Charge–Discharge) and electrochemical impedance spectroscopy (EIS) analyses in aq. 1 M KOH. The as-fabricated Co–Bi m @rGO composite showed a specific capacity of 1488 C g −1 at 1 A g −1 and maintained 96% of its initial capacitance after 8000 GCD cycles at 4 A g −1 . The superior capacity performance of the Co–Bi m @rGO composite is mainly ascribed to its mesoporous nature with an improved surface area, multiple redox sites and synergistic effect between the Co–Bi m MOF and rGO moiety. The constructed Co–Bi m @rGO//AC device showed an energy density of 90.55 W h kg −1 at a power density of 2396.28 W kg −1 , and the device showed a cyclic stability of 88% even after 4000 GCD cycles at 3 A g −1 . Further, biocompatibility analysis of the Co–Bi m MOF and Co–Bi m @rGO composite proved the non-toxic nature of the as-prepared electrode material. Thus, the effective energy storage ability of the Co–Bi m @rGO composite confirms it as a potential candidate for supercapacitors in day-to-day applications.