The crystal structure of MoS2 was characterized using STOE SEIFERT X-ray diffractometer with Cu K source (1.5406 Å, 40 kV, 30 mA). The surface morphology and lattice spacing of MoS2 were observed by scanning electron microscope (SEM, JEOL JSM 7600) and transmission electron microscope (TEM, JOEL-2100), respectively. Raman spectra were recorded with RENISHAW Raman spectrometer system using 633 nm laser. The chemical states of S and Mo in MoS2 were evaluated by X-ray photoelectron spectrometer (XPS, Thermo Scientific K-alpha photoelectron spectroscopy) with Al K- (1486.6 eV) as the X-ray source.