^aLaboratory of Physics of Materials and Nanomaterials Applied at Environment (LaPhyMNE), Gabes University, Faculty of Sciences in Gabes, 6072, Tunisia

^bDepartment of Physics, College of Sciences, Imam Mohammad Ibn Saud Islamic

University (IMSIU), Riyadh 11623, Saudi Arabia

^cPhysics Department, Assiut University, Assiut 71516, Egypt

In this work, we report the synthesis of different hybrid nanocomposites by sol-gel method. Therefore, we used picric acid as a catalyst to incorporate the nanopowder oxides of nickel (NiO), copper (CuO) and manganese (MnO) in the porous carbon matrix based on pyrogallol and formaldehyde (PF). After a drying and heat treatment for two hours at 650 °C pyrolysis temperature, the obtained materials have been characterized by different structural and electrical techniques. The X-ray diffraction (XRD) spectra show that the incorporation of inorganic nanoparticles improved the crystallization of different nanocomposites with the existance of a graphite phase. The transmission electron microscopy (TEM) images reveal that the graphite nanoparticles size depends to the incorporated inorganic oxide. From the electrical studies, we notice that electrical conduction is linked to the presence of graphite nanoparticles. The variation of the electrical conductivity and the relaxation time with the measurement temperature, ranging between 80 and 300 K, explain the effect of the hopping conduction mechanism in these nanocomposites.