Hexanediamine-assisted surface modification of ZnO nanoparticles for dielectric property tailoring and enhanced asymmetric supercapacitor device performance
摘要
The development of multifunctional nanomaterials with both superior dielectric and electrochemical properties is crucial for advancing modern electronic and energy storage technologies. In this study, hexanediamine-functionalized zinc oxide nanoparticles (ZnO NPs) were synthesized and systematically investigated. ZnO nanoparticles were successfully functionalized with 1,6-hexanediamine, and comprehensive analysis confirmed modifications in structural, optical, chemical, and morphological properties, validating the effectiveness of the functionalization process. PXRD confirmed enhanced crystallinity and increased crystallite size upon capping, while FTIR verified successful amine functionalization through characteristic NH and CH2 vibrations. Optical studies revealed a blue shift in absorption and reduced trap emissions in capped ZnO NPs due to quantum confinement, with band gaps of 3.02 eV (pure) and 2.87 eV (capped). TEM analysis confirmed improved morphology and dispersion in capped ZnO NPs with hexagonal shape and reduced agglomeration. The dielectric behavior of the functionalized ZnO NPs showed real and imaginary dielectric permittivity of 115 and 99 at 1 MHz, respectively. Additionally, the material exhibited an AC conductivity of 0.0056 Ω-1 mm-1, highlighting its potential for advanced electronic application. Furthermore, an asymmetric device was fabricated to investigate the electrochemical properties, which displayed cyclic stability. After 15,000 cycles at a current density of 15 mA cm-2, the device retained 81% of its capacitance and achieved nearly 100% Coulombic efficiency. The device also exhibited notable energy and power densities of 10.94 mWh cm-2 at 1 mA cm-2 and 5000 mW cm-2 at 10 mA cm-2, respectively. These findings underscore the device’s superior performance and long-term durability, positioning it as a desirable candidate for advanced energy storage applications. Finally, a real-time supercapacitor was demonstrated, showcasing the practical application of the functionalized ZnO NPs in energy storage technologies.