Functionalization of MoS 2 with 1,2-dithiolanes: toward donor-acceptor nanohybrids for energy conversion

The covalent functionalization of exfoliated semiconducting MoS2 by 1,2-dithiolanes bearing an ethylene glycol alkyl chain terminated to a butoxycarbonyl-protected amine and a photoactive pyrene moiety is accomplished. The MoS2-based nanohybrids were fully characterized by complementary spectroscopic, thermal, and microscopy techniques. Markedly, density functional theoretical studies combined with X-ray photoelectron spectroscopy analysis demonstrate preferential edge functionalization, primarily via sulfur addition along partially sulfur saturated zig-zag MoS2 molybdenum-edges, preserving intact the 2D basal structure of functionalized MoS2-based nanohybrids as confirmed by high-resolution transmission electron microscopy and electron energy loss spectroscopy. Furthermore, in the MoS2-pyrene hybrid, appreciable electronic interactions at the excited state between the photoactive pyrene and the semiconducting MoS2 were revealed as inferred by steady-state and time-resolved photoluminescence spectroscopy, implying its high potentiality to function in energy conversion schemes. MoS2 can be chemically functionalized with organic functional units, to develop innovative hybrid materials suitable for energy conversion. Collaborative efforts between experimental and modeling teams at the Theoretical and Physical Chemistry Institute—National Hellenic Research Foundation, Greece, Institut des Materiaux Jean Rouxel—CNRS Nantes, France, Instituto de Nanociencia, Universidad de Zaragoza, Spain, and Chimie des Interactions Plasma-Surface, University of Mons, Belgium, reveal that chemical functionalization occurs preferentially on MoS2 edge sites. When photoactive components are attached to MoS2 edges, visible light illumination promotes efficient charge transfer within the hybrid material. Research along those lines may result in the construction of innovative solar and photoelectrochemical cells with high efficiencies.