Investigations on structural, microstructural, dielectric and electrical conductivity of the ZnO-MWCNTs nanocomposite synthesized via sol-gel method

In our present work, we used cost effective sol-gel process to synthesize pure zinc oxide (ZnO-P), ZnO-MWCNTs nanocomposites with different MWCNTs concentrations: 5 wt.% (ZnO-5) and 10 wt.% (ZnO-10). The impact of varying concentration of MWCNTs on structural, microstructural and dielectric properties of ZnO-MWCNTs nanocomposites have been thoroughly examined. X-ray diffraction (XRD) analysis reveals that the ZnO-P possess a hexagonal wurtzite phase structure. As the concentration of MWCNTs in the ZnO increases, the peak broadening becomes more pronounced. In the Raman spectra of the ZnO nanorods, a sharp and intense peak was detected around 437 cm⁻¹, corresponding to the high-frequency branch of the E₂ mode of ZnO. I_D/I_G ratios for pure MWCNTs, ZnO-5 and ZnO-10 are 0.643, 0.723 and 0.840 respectively. TEM analysis shows nanorod-like structure of ZnO and SAED pattern of ZnO-MWCNTs nanocomposite confirms the structural integrity of nanocomposite material. Lattice- spacing of MWCNTs has been calculated 0.357 nm by IFFT image. The frequency dependence behaviour of the dielectric constant (𝜀'), dielectric loss factor (tan δ), and a.c. conductivity of ZnO-P, ZnO-5, and ZnO-10 has been measured. The dielectric properties of these samples possess behaviour consistent with the Maxwell-Wagner model and Koops phenomenological theory. The improvement in dielectric properties of ZnO-MWCNTs nanocomposites as compared to ZnO makes them a suitable candidate for energy storage applications.