Temperature Assisted Ligand Conversion from 3R-MoS2 to α-MoO3 by Preserving Layered Nature

Abstract

All polymorphs of 2D MoS2 (1T, 2H & 3R) are layered with planes of molybdenum atoms sandwiched between two sulphur atoms (S-Mo-S layers) with intra planar covalent bonding and weak interlayer van der Waal’s interactions. Here in this work, the role of polyethylene glycol as surfactant in the formation of 3R-MoS2 is recognized. XRD and FTIR results provide structural elucidation and bonding information in the compound. More detailed crystal structure investigations and polyhedral visualizations were obtained in the Rietveld refinement procedure. The trigonal prismatic metal coordination in the 3R phase is portrayed with the ABC-ABC type layer stacking sequence. The morphology of layered 3R-MoS2 nanostructure was identified from HRTEM images and the percentage composition from FESEM mapping and EDAX analyses. Temperature dependent mass loss in the compound is monitored and the quantitative analysis confirms the complete transformation of 3R-MoS2 -MoO3 at a temperature of 398 °C. Endo and exothermic peaks in the DSC and DTA measurements help to substantiate the results. Thus the work highlights the temperature assisted conversion of sulphide (3R-MoS2 -MoO3) of molybdenum at 398°C by cleavage of S-S bonds and preserving the layered nature.