Effect of metal oxide nanoparticles XO (X = Ni, Cu, Mn) on the physical properties of hybrid organic/inorganic nanocomposites

Hybrid organic/inorganic nanocomposites were synthesized by sol-gel technique after the incorporation of nickel oxide (NiO), copper oxide (CuO) and manganese oxide (MnO) nanoparticles (NPs) in carbon matrix based on pyrogallol and formaldehyde (PF) using picric acid as catalyst. After a drying step, the samples were heated for 2 hat different pyrolysis temperatures between 600 and 1000 degrees C in tubular furnace under open nitrogen atmosphere. The obtained samples have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), direct current (dc) and alternating current (ac) techniques in the measurement temperature range between 80 and 300 K. The XRD spectra show that PF matrix is amorphous even after thermal treatment at 1000 degrees C. On the other hand, the different nanocomposites PF/NiO, PF/CuO and PF/MnO are crystallized with the appearance of the graphite structure at high pyrolysis temperature. The temperature dependence conductivities can be explained by Godet-Variable Range Hopping (3D-GVRH) conduction model in all samples with the presence of an exponential distribution of localized states. The ac investigation shows the dominance of semiconductor or metallic behaviour, depending on the metal oxide NPs incorporated and the pyrolysis temperature.