In this study, we report a new method for the quick, green, and one-step preparation of few-layered molybdenum disulfide (MoS2) nanosheets with wide bandgap. MoS2 nanosheets with small lateral dimension and uniform size distribution were synthesized for various applications. MoS2 powder was synthesized using the hydrothermal method; then, thinned by applying laser irradiation with different energies from 40 to 80 mJ. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectra, and photoluminescence (PL) spectra were applied for the characterization of the MoS2 nanosheets in terms of morphology, crystal structures, and optical properties. The widest calculated bandgap 4.7 eV was for the sample under 80 mJ laser energy. The results confirmed the successful preparation of highly pure, uniform, and few-layered MoS2 nanosheets. Furthermore, it was possible to enhance the production rate of MoS2 nanosheets (including nanosheets and nanoparticles) through laser irradiation. Thus, the present paper introduces a simple and green alternative approach for preparing few-layered MoS2 nanosheets of transition metal dichalcogenides or other layered materials.
Magnesium oxide (MgO)-graphene oxide (GO) nanocomposites were prepared by the hydrothermal method at different temperatures. The effect of growth temperature on the structural, linear, and nonlinear optical (NLO) parameters was investigated. The decoration of MgO on GO sheets was confirmed by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and UV-visible (UV-vis) spectroscopy analyses. The energy band-gaps of MgO-GO nanocomposites were calculated from UV-vis spectrum using Tauc plot. The NLO parameters of MgO-GO nanocomposites were calculated for the first time by the simple Z-scan technique with nanosecond Nd:YAG laser at 532 nm. The nonlinear absorption coefficient β and nonlinear refractive index n 2 for MgO-GO nanocomposites at the laser intensity of 1.1 × 10 8 W/cm 2 were measured to be in the order of 10 −7 cm/W and 10 −12 cm 2 /W, respectively. The third-order NLO susceptibility of MgO-GO nanocomposites was measured in the order of 10 −9 esu. The results showed that MgO-GO structures have negative nonlinearity as well as good nonlinear two-photon absorption at 532 nm. Furthermore, the NLO parameters increased by the enhancement of the growth temperature. As the investigation of new materials plays an important role in the advancement of optoelectronics, MgO-GO nanocomposites possess potential applications in NLO devices.
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