Novel ZIF-8/ZIF-67 and multi-wall carbon nanotubes ternary composite: A promising electrode material for high capacitance supercapacitors

Abstract

The increasing demand for advanced energy storage devices drives research into innovative and high-performance composite materials. Among these are hybrid materials made of carbon-based substances such as carbon nanotubes and metal-organic frameworks (MOFs), which exhibit advanced electrochemical properties compared to single-component systems. This work used the solution mixing and self-assembly method to synthesize a novel ZIF-8/ZIF-67/MWCNT composite with unique structural and electrochemical properties. XRD analysis confirmed the crystalline structure of the composite, and FTIR and Raman spectra further validated the successful integration of ZIF-8, ZIF-67, and MWCNTs. Further, SEM analysis gave an average particle size of 2.38 μm, and BET results showed a low surface area of 0.2001 m²/g and an average pore size of 523.1 Å that promotes ion transport. The rough surface of this composite contributed to enhanced electrochemical performance, showing a hybrid behavior and achieved a specific capacitance of 194.48 F/g at 0.8 A/g, with an energy density of 3.90 Wh/kg and a power density of 152 W/kg, respectively. The composite also retains 50.12 % of its initial capacitance after 3000 cycles at a higher scan rate of 100 mV/s, demonstrating excellent cyclic stability even under such higher scan rates. These results point to ZIF-8/ZIF-67/MWCNT composite as a promising candidate for high-performance supercapacitor applications, utilizing the combined advantages of EDLC and pseudocapacitance.