Synthesis and characterization of cobalt(III) oxide -carbon nanotube hybrid nanostructures and their photocatalytic dye degradation
摘要
In this study, nanocomposites of carbon nanotubes (CNTs) with Co3O4 nanoparticles (CNT@Co3O4) were synthesized using a modified hydrothermal method and investigated their photocatalytic activity toward degradation of methylene blue (MB) dye. The X-ray diffraction (XRD) results showed the presence of crystalline phase of cobalt oxide. Moreover, field emission scanning electron microscopy (FESEM) images confirmed the distribution of spherical particles (diameter ≈ 30–50 nm) on the surface of CNTs. In the Raman spectra, the D and G bands of CNT were observed, and the characteristic bands of cobalt oxide were also detectable. Optically, the band gaps obtained for CNT, Co3O4 and CNT@Co3O4 were calculated to be ≈ 5.46, 5.64 and 4.56 eV, indicating a decrease in the nanocomposite band energy and an improvement in relative optical absorption. The PL spectra showed a decrease in reflectance from electron–hole recombination in the bound sample, which is consistent with the increase in photocatalytic efficiency. The photocatalytic activity under solar irradiation was measured using a methylene blue solution (C₀ = 10 mg L⁻1). The results showed that CNT@Co3O4 had the best performance; the degradation efficiencies of MB for CNT, Co3O4 and CNT@Co3O4 were reported to be about 41%, 64% and 77% after 180 min (and at shorter time intervals CNT@Co3O4 consistently showed superior performance). The greater efficiency of the nanocomposite is mainly explained by the more efficient separation of charge carriers, faster transfer of electrons to the CNT and increased number of surfactant sites.