Controllable synthesis by hydrothermal method and optical properties of 2D MoS2/rGO nanocomposites

In this research, 2D-MoS2/rGO nanocomposites were successfully synthesized by a facile hydrothermal method using graphene oxide (GO), sodium molybdate (Na2MoO4) and thiourea (CH4N2S) as the reactants. The effect of hydrothermal temperature (180-240 degrees C) on structure and optical properties of the MoS2/rGO have been systematically investigated. The study of chemical composition, structural and morphological properties was performed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS) and Raman spectroscopy, while the optical properties were measured using photoluminescence spectroscopy. The FESEM and HRTEM results revealed that the ultrathin MoS2 nanosheets with thickness in the range of similar to 6-13 nm (similar to 6-8 layers) and average lateral size of similar to 130-330 nm were uniformly dispersed on the GO surface. Both the XRD and Raman analyses confirm that the MoS2 sheets in all prepared samples have a hexagonal phase structure (2H-MoS2). By increasing hydrothermal temperature, the characteristic diffraction peak (002) of 2H-MoS2 phase (at 2 theta approximate to 14.2-14.5 degrees) becomes sharper and its intensity gradually increases, thereby showing a very strong preferential orientation and better crystal quality. The estimated optical band gap for MoS2/rGO is achieved in the range of similar to 1.56-2.38 eV and it seems to be controlled by adjusting the synthesis temperature. Our work underscores the principle that controlling hydrothermal reaction temperature may constitute a generic strategy for modifying microstructure and engineering the optical bandgap of these semiconductor 2D nanocrystals, which opens the possibility of its use in electronic applications. [GRAPHICS] .

Automated summary

2D-MoS2/rGO nanocomposites were successfully synthesized using a hydrothermal method. The effect of hydrothermal temperature on the structure and optical properties of the material was investigated. Increasing the temperature resulted in improved crystal quality and optical bandgap, suggesting potential applications in electronic devices.