Synthesis and structural characterization of MoS2 nanospheres and nanosheets using solvothermal method

This paper reports the solvothermal synthesis of MoS2 nanospheres and nanosheets. The nanospheres were obtained using ammonium polysulfide as a sulfur source and have a mean diameter of about 100 nm. The nanosheets were assembled from a few lamellar layers and were obtained using thiourea as a sulfur source. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used in order to characterize the prepared powders. Conglomerate size and stability of the synthesized samples in hexane were studied with zeta potential. The four-ball method was used to assess the lubricating effect when these materials were used as additives in engine oil dispersions. The topography of the wear scar was analyzed using SEM, EDX, and 3D surface profilometry. The tribological properties of base engine oil containing the nanomaterials penetrated more easily into the interface space, and it formed a tribo-film at contact interface. The tribological performance showed that the synthesized nanosheets had superior anti-wear and friction-reducing properties as a lubrication additive compared with nanospheres, and the wear scar of balls lubricated with nanospheres revealed larger width compared to nanosheets. From the results, it is observed that nanosheets dispensed in oil have better tribological performance compared to nanospheres oil in terms of capability to reduce wearope

Co-precipitation synthesis and characterization of faceted MoS2 nanorods with controllable morphologies

Molybdenum disulfide (MoS2) nanopowder has been prepared using a co-precipitation method. This paper describes the thermal effect on the morphology enhancement of MoS2 sphere-like structures into nanorods with a winding structure. For the reduction in precursors, the as-obtained MoS2 nanopowder was calcinated at 250, 400, 600, and 800 degrees C for 1 h in an N-2 environment. The calcined samples were characterized using a particle size analyzer, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with X-ray analysis (EDAX) and transmission electron microscopy, HRTEM and X-ray photoelectron spectroscopy. The results show the MoS2 sphere-like structure with diameter in the range of 50-100 nm and rod-like winding structure with diameter in the range of 20-150 nm, and a few tens of micrometers in length with a high degree of size homogeneity. The FT-IR spectra show the obtained bands at 480 and 900 cm(-1) are corresponding to the Mo-S bond and the S-S bond. The TG-DTA curves confirm the thermal stability of the prepared samples. It is observed that the band gap energy for the MoS2 nanorods is lower than for the nanospherical structure MoS2, which leads to achieve high electron and hole recombination rate.ope