Auto-oxidation of exfoliated MoS2 in N-methyl-2-pyrrolidone: from 2D nanosheets to 3D nanorods

There has been a great deal of interest in the electrochemical intercalation of two-dimensional materials in recent years, with studies of transition metal dichalcogenides (TMDs), a so-called "beyond graphene" material, coming to the fore in the context of energy storage devices. However, the electrochemical intercalation properties of these materials are restricted, especially in an aqueous environment, because of the limit of interlayer spacing between adjacent TMD (here, MoS2) layers. We have therefore introduced a novel preparation route for MoO3 nanorods from exfoliated 2H-MoS(2)via the auto-oxidation of a mixture of N-methyl-2-pyrrolidone and water via the sonication-assisted exfoliation of MoS2. It is found that the MoO3 center dot MoS2 free-standing electrode displays a larger interlayer spacing than the MoS2 electrode, which exhibits a capacitance roughly ten times higher than that of traditional 2H-MoS2. This study expands on the behaviour of ion intercalation in aqueous media of transition metal dichalcogenides (TMDs) and transition metal oxide (TMOs) materials, which can be of use in various electrochemical applications such as energy storage devices.