Synthesis, characterization of graphene, BN, MoS2, TiS3 and investigation of photophysical properties of water-soluble graphene/dye composites

Graphene, as one of single-atom-thick carbon nanomaterial, has recently interested among researchers due to its superior optical and electrical properties. Graphene's high crystal, mechanical (E=1,0TPa), electrical, thermal (k=5000 Wm-1K-1) and optical (Optical Transmittance=% 97.7) properties have attracted the widespread attention of the researchers. After graphene discovering, boron nitride (BN), titanium trisulfide (TiS3), molybdenum disulfide (MoS2), tungsten disulfide (WS2) etc. are a fundamentally new types of 2D electronic material exhibits extraordinary properties. Dyes are frequently used optical materials in medical and technological applications. Optical and morphological characterization of nanocomposites that is obtained by using these materials and dyes have great importance for potential applications such as optical sensors, optoelectronic devices, etc. Xanthene derivatives are one of the best dyes used in obtaining nanocomposits since they have several characteristic features including large absorption and fluorescence, light resistance, low toxicity in-vivo, and relatively high solubility in water. In this thesis, graphene, BN, MoS2 and TiS3 were synthesized using micromechanical method and their dimension analyzes were carried out by optical microscope, Raman and AFM spectroscopy. As a result of the analyzes, it was determined that single, double and multilayered graphene, BN, MoS2 and TiS3 with thickness of about 1 nm was synthesized. Secondly, reduced graphene oxide (rGO)was synthesized with modified Hummers' method. novel composites with rGO and xanthene derivative dyes (Rhodamine 101, Florescein and Eosin Y) were synthesized in an aqueous medium. Morphological and optical properties of these composites was confirmed with X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy and steady-state fluorescence spectroscopy. The effect of rGO and dye concentrations on optical and morphological properties of synthesized composites was investigated. Various changes (such as bathochromic and hypsochromic shift, hypochromic effect) were observed in the absorption spectra of the composites depending on the amount of rGO. Also, when amounts of rGO in composites was increased, the fluorescence intensities of dyes were influentially quenched.