Surface Engineering of Chemically Exfoliated MoS2 in a “Click”: How To Generate Versatile Multifunctional Transition Metal Dichalcogenides-Based Platforms

Abstract

The interest for transition metal dichalcogenides (TMDs) as two-dimensional (2D) analogues of graphene is steadily growing along with the need of efficient and easy tunable protocols for their surface functionalization. This latter aspect holds a key role in the widespread application of TMDs in various technological fields and it represents the missing step to bridge the gap between the more popular C sp2-based networks and their inorganic counterparts. Although significant steps forward have already been made in the field of TMDs functionalization (particularly for MoS2), a rational approach to their surface engineering for the generation of 2D organic–inorganic hybrids capable to accommodate various molecules featured by orthogonal groups has not been reported yet. The paper paves the way toward a new frontier for “click” chemistry in material science. It describes the post-synthetic modification (PSM) of covalently decorated MoS2 nanosheets with phenylazido pendant arms and the successful application of CuAAC chemistry (copper-mediated azide–alkyne cycloaddition) towards the generation of highly homo- and hetero-decorated MoS2 platforms. This contribution goes beyond the proof of evidence of the chemical grafting of organic groups to the surface of exfoliated MoS2 flakes through covalent C–S bonds. It also demonstrates the versatility of the hybrid samples to undergo post-synthetic modifications thus imparting multimodality to these 2D materials. Several physico-chemical [SEM microscopy, fluorescence lifetime imaging (FLIM)], spectroscopic (IR, Raman, XPS, UV–vis), and analytical tools have been combined together for the hybrids’ characterization as well as for the estimation of their functionalization loading.