Nanomaterials based on MoS2 are very versatile; MoS2 nanoparticles are proven catalysts for processes such as hydrodesulphurization and the hydrogen evolution reaction, and transition metal dichalcogenides in general have recently emerged as novel 2D components for nanoscale electronics and optoelectronics. The properties of such materials are intimately related to their structure and dimensionality. For example, only the edges exposed by MoS2 nanoparticles are catalytically active, and extended MoS2 systems show different character (direct or indirect gap semiconducting, or metallic) depending on their thickness and crystallographic phase. Here, we show how the interaction with a metallic support can also have a significant effect on both the structure and properties of nanostructured MoS2. We will first address results from density functional theory (DFT) calculations investigating how support interactions affect MoS2 nanoparticles of varying size, composition, and structure. In particular, we will show how edge terminations and crystallographic phases that are metastable for free-standing nanoparticles are greatly stabilized upon interaction with a metal surface, leading to changes in the electronic and chemical properties of the active sites. These support effects are strongly size-dependant, which explains differences in the structural phases observed for supported MoS2 NPs. We will also discuss the free energies of these supported nanoparticles on the basis of ab initio thermodynamics analyses, which allow exploring how support interactions are affected by varying temperature and pressure. We will thus demonstrate that the properties of nanostructured MoS2 can be modified via support interactions, suggesting the possibility of tailoring MoS2 function through the choice of supporting materials.

Size and substrate induced phase stability of MoS2 nanoparticles under varying conditions

254th National Meeting (2017)

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