Study of the dielectric properties of graphene/CuS/ZnO hybrid nanocomposites for high performance supercapacitor applications

Abstract

We report here the dielectric characteristics of a potential nanocomposite consisting of graphene doped with CuS nanoparticles and ZnO nanotubes for supercapacitance applications. The as synthesized nanoparticles were characterized using X-ray diffraction (XRD), Raman spectroscopy and High Resolution Transmission Electron Microscopy (HRTEM). By varying temperature and frequency, the dielectric characteristics of the as synthesized graphene (Gr), graphene–CuS–ZnO hybrid nanocomposite (GCZ) and graphene–ZnO hybrid nanocomposite (GZ), were investigated and compared. Complex impedance analysis showed that the capacitance characteristics of the as synthesized samples had increased with increasing frequency and temperature. The Nyquist plots of the as synthesized samples at different temperatures and frequencies confirmed that the as synthesized GCZ show better conductivity than the as synthesized GZ and Gr. The temperature and frequency dependency of the dielectric permittivity (ε′) and dielectric loss (tan δ) of all the as synthesized samples were investigated. The as synthesized GCZ shows the highest dielectric permittivity than the as synthesized GZ and Gr due to the interfacial polarisation. The order of dielectric loss of the as synthesized samples is as follows GCZ ≫ GZ > Gr due to a significant increase in the conductivity of GCZ. The results indicated that the as synthesized GCZ possesses a high surface area and high electric conductivity which provide a promising material for capacitance applications.