Hydrothermally synthesized 2H-MoS2 under optimized conditions – A structure and morphology analysis

Abstract In this study, we obtained the optimized conditions to synthesize pure semiconducting 2H-MoS 2 nanomaterial, using a facile and scalable hydrothermal route under the variation of growth parameters such as reaction temperature, reaction time and sulfur precursors. The structural and phase identification of obtained MoS 2 powders was analysed using XRD and raman spectroscopy. The reproducible formation of pure 2H-MoS 2 phase is reported for the optimized reaction time of 22 h at a temperature of 200 °C using thiourea as sulfur source, with a high yield of 77.4%. FESEM analysis revealed nanoflower-like morphology of average diameter of 300–400 nm with identifiable petals of thickness ∼25 nm for the formed 2H-MoS 2 under the optimized conditions. The crystallite size, strain and dislocation density were estimated theoretically using Williamson-Hall plots for the MoS 2 formed under the variation of growth temperatures. Tensile strain values were obtained for MoS 2 formed using thiourea, which correlated only with phase transitions from mixed 1 T/2H-MoS 2 to pure 2H-MoS 2 . In contrast, only mixed 1 T/2H-MoS 2 phase were obtained for MoS 2 powders using L-Cysteine, and correspondingly the strain values were extremely small, which may be due to no phase transition observed and presence of nanosheets without curved petal-like features. The results of this study provide optimized condition for the formation of semiconducting 2H-MoS 2 nanomaterial by a scalable route. This is useful for low-cost fabrication of flexible nanoelectronic devices such as non-volatile ReRAMs, supercapacitors and sensors based on 2H-MoS 2 .