▎ 摘　　要

Zirconium substituted magnesium cobalt ferrite (ZrxMg0.2-xCo0.8-xFe2O4) nanoparticles and their nano-heterostructures with graphene were synthesized by co-precipitation and ultra-sonication route respectively. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopic (SEM) analysis was done to study the effect of Zr4+ substitution on structural properties, surface morphology, dielectric and current-voltage properties of nanoparticles. The crystallite size of nanoparticles was found in the range of 23-28 nm. XRD pattern analysis confirmed the spinel structure of nanoparticles. Graphene synthesized by modified Hummer's method was utilized as substrate to prepare the heterostructures with ferrite particles. Dispersion of nanoparticles on the surface of rGO sheets was confirmed by SEM analysis. Enhanced photocatalytic activity of nanoparticles and graphene based nano-heterostructures was observed under visible light irradiation. During the current-voltage measurements, decrease in electrical resistivity of nanoparticles was observed. Dielectric measurements were performed within the frequency range 1 MHz-3 GHz. Electrochemical impedance spectroscopy was done to evaluate the kinetic parameters and charge-transfer resistance (R-ct) at electrode interface. Enhanced photocatalytic applications, suggested that ZrxMg0.2-xCo0.8-xFe2O4 nanoparticles and graphene based nano-heterostructures can be used for degradation of various organic based pollutants in drinking water.