Hydrothermal synthesis of hematite-GO nanocomposites at different GO contents and potential application in nonlinear optics

A hydrothermal method was applied to synthesize hematite-GO nanocomposites at different GO levels and Z-scan technique was used to consider the nonlinear optical properties of products. To obtain insights into structural, chemical-bond, morphological and optical properties in hematite-GO nanocomposites by increasing GO contents, X-ray diffraction, Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), UV-VIS spectroscopy were performed. The measurements were done on a series of powders with various contents of GO from 0 up to 50 mg. The analyses revealed that GO nanosheets operate as supporting materials for attaching the hematite particles so that the crystallite sizes of the hematite-GO nanocomposites decreased with increasing the GO contents. A decrease in energy band gaps was observed from 5.41 up to 5.34 eV calculating from UV-VIS spectra. Z-scan measurements depicted a high nonlinear optical absorption and a negative nonlinearity relating to the reversed saturable absorption along with two-photon absorption and self-defocusing phenomenon, respectively. The third-order optical susceptibilities, chi((3)), were estimated of the order of 10(-s) esu which reached to 10(-4) esu for hematite-GO nanocomposites with 50 mg of GO. The results not only introduce an optimal state for GO contents which attributed to the 50 mg of GO levels but also open a new avenue to synthesize new graphene-based nanocomposites in nonlinear optics area by tuning of GO contents.