Molybdenum is a versatile element because can form many compounds with oxygen and sulfur, like molybdenum trioxide and molybdenum disulfide. With the advent of two-dimensional materials, these compounds have gained new properties and applications, especially in supercapacitors and batteries. The synthesis and processability of 2D materials it’s a major drawback, many cases involve toxic solvents and complexes syntheses like chemical vapor deposition and hydrothermal synthesis. In this work we developed a simple route to synthesized three materials from one synthesis: i) amorphous molybdenum sulfide and oxide (MoX), ii) molybdenum trioxide (MoO3) and iii) molybdenum disulfide (MoS2) from the reaction of ammonium molybdate and ammonium sulfide in acidic media, with further annealing in an ambient and inert atmosphere in distinct temperatures. These materials are processed with liquid-phase exfoliation and after the thin film are formed from dispersion through liquid-liquid interfacial method adapted from route developed earlier in the group. With no annealing the material is amorphous and it is a mixture between molybdenum sulfide and oxide, which was confirmed by Raman spectroscopy. With the annealing in an inert atmosphere, the mixture was composed of MoS2 and MoO3, and a distinct behavior was observed when the material was processed through the liquid-liquid interfacial method, getting a thin film composed only of MoS2, confirmed by Raman spectra with shows the bands E2g (385 cm-1) and A1g (408 cm-1). In the case of annealing at ambient atmosphere, only α-MoO3 was obtained and XRD data shows the presence of an orthorhombic phase, with a lamellar structure which can be also seen in SEM images. This route can be easily adapted to the formation of nanocomposites with 2D materials as shown in this work with graphene oxide (GO) and black phosphorus (BP) as a proof of concept. In conclusion, we show the versatility and multifunctionality of the route to obtain different compounds and the simplicity of the liquid-liquid interfacial method for separate the mixtures formed, which is necessary to evaluate the properties and applications of each material.

Liquid-liquid interfacial route to different molybdenum-based materials

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