Zinc oxide/multiwalled carbon nanotubes composites modified with bowstring hemp for enhanced supercapacitive performance

Official URL: https://dx.doi.org/10.1002/slct.202503559

This paper describes an ecofriendly and cost-effective method for the synthesis of high-performance energy storage materials through biogenic synthesis of zinc oxide–modified multiwalled carbon nanotube (ZnO/MWCNT) nanocomposites. Calotropis gigantea (bowstring-hemp) leaf extract was employed as a biogreen reducing and capping agent to synthesize ZnO/MWCNT composites with varied MWCNT loadings of 1%, 2%, and 3%, labeled as ZOM-1, ZOM-2, and ZOM-3, respectively. Structural integrity and mesoporous character of the materials were confirmed by thorough characterization with XRD, FTIR, FESEM, BET, and HRTEM. Among the samples, ZOM-2 (ZnO:MWCNT = 1:2) possessed the maximum surface area of 70.419 m²/g and an excellent specific capacitance of 563.19 F/g at a scan rate of 1 A/g. It retained 98% of the capacitance even after 10,000 charge–discharge cycles at 10 A/g, which indicates excellent stability. Apart from that, ZOM-2 also registered a power density of 364.5 W/kg and an energy density of 63.35 Wh/kg. These findings are promising in C. gigantea-aided green synthesis as a process for the fabrication of sustainable, cost-efficient, and high-performance supercapacitor materials for next-generation energy storage devices.