Synthesis and characterization of microporous carbon matrix enriched by MnO2 nanoparticles

Nanocomposites (RF/MnO2) based on resorcinol–formaldehyde (RF) as carbon matrix and manganese oxide nanoparticles (MnO2) as incorporated material were elaborated by a sol–gel method. The effect of pyrolysis temperature was studied using different characterization techniques. Firstly, the Raman results show two strong peaks referred to G and D bands of carbon and an additional one related to MnO2. Also, it reveals a change in the degree of graphitization when the temperature increases. This result suggests also the successful incorporation of the MnO2 into the matrix, which was confirmed by the FTIR analysis. Then, dc measurement proves that the behavior of the nanocomposite changed from insulator to metallic one when the pyrolysis temperature increased from 600 to 1000 °C passing through a sudden transition explained by a percolation phenomenon. The X-ray diffraction confirms the previous results concerning the temperature effect. More than this, it proves that the nanocomposites are partially crystallized with the appearance of the graphite structure, the manganese dioxide (MnO2), the manganese oxide (MnO), and the metallic manganese (Mn) at high pyrolysis temperature. The scanning electronic microscope (SEM) images depict the porous structure of the RF matrix. Finally, the electrical behavior and dielectric properties were in good agreement with the other results; they confirm the effect of the pyrolysis temperature on the electrical conductivity and the dielectric loser. The properties of the obtained nanoporous conducting carbon/manganese nanocomposite can be adjusted by the pyrolysis temperature which makes this material promising for many technological applications.
This work was financially supported by the Tunisian Ministry of Higher Education and Scientific Research through the budget of the Tunisian Laboratories. And it was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding Contract UIDB/04650/2020.