Tuning the dielectric characteristics and energy storage properties of Ni-ZnO/rGO nanocomposite

Abstract

In the present study, pure and Ni-doped ZnO/rGO nanocomposites (NCs) are reported using the cost-effective wet chemical route to explore their dielectric characteristics. The structural examinations using X-ray diffraction (XRD) exposed the hexagonal wurtzite structure in both pure and Ni doped ZnO samples. The presence of an additional secondary phase accredited to NiO was also observed in Ni doped sample. The microstructural investigations using scanning electron microscope (SEM) revealed that Ni addition in ZnO modified particle size, shape, and distribution. Using tunneling electron microscope (TEM), it demonstrated that nanoparticles are well distributed in rGO sheets. The dielectric constant and dielectric loss of NCs increased with rGO addition at low frequency region. The relatively higher observed value of the dielectric constant while lower loss is explained on the basis of oxygen vacancies generated. The ac conductivity of NCs increased gradually with frequency due to the tunneling and hopping mechanisms. These results demonstrated that the higher carrier generations at the interface between rGO and ZnO grains are due to the increased mobility of charge carriers. Thus, the synergetic effect among them has the potential for use in advanced microelectronic devices, for instance, a gate material in transistors, capacitance-based energy storage devices etc.