Síntese, caracterização e aplicação de nanoestruturas tridimensionais de grafeno decoradas por nanopartículas de óxidos de metais de transição

Abstract

This work consists of the synthesis, characterization and application of threedimensional graphene nanocomposites decorated with nanoparticles of MnFe2O4 and NiCo2O4. The nanocomposites were synthesized by the spray pyrolysis method, in which it was possible to obtain crushed graphene/metallic precursor nanocomposites in a single step. Obtaining crumpled graphene called crumpled graphene (CG) somehow avoids stacking graphene sheets. One way to add new properties to the aforementioned carbon nanostructure is to decorate it with transition metal oxide nanoparticles, seeking to add electrochemical properties. The differential of this work is the control over the shape and composition of the nanocomposites, evaluating the synergistic effect (CG / Fe / Mn and CG / Ni / Co) in different proportions. The nanocomposites were characterized by Raman spectroscopy, X-ray diffraction, scanning and transmission electron microscopy, cyclic voltammetry and chronoamperometry. After the morphological and structural characterizations of all materials, it was found that the morphology of these composites is similar to kneaded paper balls, with control over the composition of the nanocomposites, in which the presence and amount of these oxides are controlled by the synthesis conditions. A study of application in H2O2 sensors was carried out, obtaining the best responses for composites 1:1:1 CG / Fe / Mn (with detection limit and sensitivity of 0.61 × 10−6 mol L−1 and 0.261 AM−1 cm−2) and CG / Ni / Co in a ratio of 1:5:5 (with detection limit and sensitivity of 0.16 × 10−6 mol L–1 and 0.550 AM−1 cm−2). Additionally, two H2O2 detection techniques were compared, highlighting the chronoamperometry technique, which presented better response and less complex analytical parameters.