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LASCOVA-BACIU, Renata; LOSHMANSKY, Constantin; SIMINEL, Anatolii; MICU, Alexandru; NEDELEA, Vitalie; KULYUK, Leonid. Synthesis and characterization of MoS2 nanosheets. In: Materials Science and Condensed Matter Physics. Ediția a 9-a, 25-28 septembrie 2018, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2018, p. 324.
|Materials Science and Condensed Matter Physics
Ediția a 9-a, 2018
Conferința "International Conference on Materials Science and Condensed Matter Physics" |
Chișinău, Moldova, 25-28 septembrie 2018
Two-dimentional layered transition metal dichalcogenide materials (TMD) are a subject of intense research for a wide variety of applications (e.g., electronics, photonics, and optoelectronics) due to their unique physical properties. However, preparation of nano sized MoS2 particles is still a challenge, which involves some difficulties and restricts its further application. Here we present a description of a hydrothermal method  providing the synthesis of MoS2 nanosheets by interaction between sodium molybdate (Na2MoO4•2H2O), as molybdenum precursor, and thioacetamide, as sulfur precursor. The precursors were dissolved in distillated water. Reactions were modified by using two different concentrations of precursors and different thermo profiles. The suspension was then transferred into a teflon-lined stainless steel autoclave, heated with a speed of 67oC/h and maintained at 220 oC during 24 hours, after that cooled with a speed 130oC/h up to room temperature. The obtained content was filtered and then the filtrate was centrifuged for 30 minutes at 6000 rpm. The samples were subjected to X-ray fluorescence analysis, whereby it was found that the samples consisted of molybdenum and sulfur. The optical absorption and photoluminescence (PL) spectra were also investigated. A typical PL spectrum at cw-excitation (λex=532nm) of the sample is presented in Fig. 1. On a broadband background, an explicit peak is observed at 1.87eV (λmax=0.66μm), which corresponds to the energy of the direct excitonic transitions in the MoS2 monolayer . The nature of the broadband luminescence with a maximum at 1.6eV can be due to the presence of flakes (nanosheets) containing several monolayers in the sample. The position of the PL spectrum of each flake depends on the number of monolayers in it and can change in a wide spectral region . The overlapping of spectral bands of flakes with a different content of monolayers provides the nonhomogeneous broadening of the integral spectrum.