The effect of liquid nitrogen-microwave treatments on the structural, optical, and tribological properties of WS2 nanoflakes

WS2 was successfully synthesized by the hydrothermal method under various liquid nitrogen and microwave treatments. X-ray diffraction (XRD) analysis showed the presence of multiple WS2 phases, of which hexagonal was the dominant phase. The morphology of the samples was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and WS2 exfoliation was confirmed after liquid nitrogen and microwave treatments. Fourier transform infrared spectroscopy (FTIR) confirmed WS2 exfoliation during the exfoliation process. Optical bandgap calculation showed an increase in the exfoliation WS2 bandwidth to 4.7 eV, which is large enough for the massive indirect bandwidth (1.3 eV) of WS2, indicating the effect of quantum confinement. Decreased photoluminescence (PL) showed the production of defects in the samples during the processes. The tribological properties of WS2 nanoflakes as an additive in oil showed that the coefficient of friction and wear performance of the oil were significantly improved by adding WS2 nanoflakes synthesized by the hydrothermal method under different liquid nitrogen and microwave treatments. The results show that WS2 nanoflakes with an improved coefficient of friction and wear performance can be a promising additive that could open a new avenue for the large-scale production of tribological materials.

The effect of liquid nitrogen-microwave treatments on the structural, optical, and tribological properties of WS2 nanoflakes Keywords:

Freezing , heating , Tribology , friction coefficient , Environmental friendly