MoS2 Domains on TiO2-Based Nanostructures: Role of Titanate/TiO2 Transformation and Sulfur Doping on the Interaction with the Support

Abstract

MoS2/TiO2-based hybrid structures have been synthesized, via a bottom-up approach, by sulfidation, with CS2 as sulfiding molecule, of molybdenum oxide precursor supported on high surface area hydrogen titanate nanotubes (HTNTs). The evolution of morphology and structure of the support, moving from titanates to TiO2 phases together with the simultaneous formation of MoS2 nanosheets have been imaged by means of AFM, HRTEM microscopies, while the vibrational and the optical properties have been investigated by FTIR and UV–visible techniques after each step of the process. More in detail, the different stacking degrees, the size distribution of the MoS2 nanosheets, decorating the heterogeneous supports, have been carefully obtained by means of HRTEM. In order to explore the nature of the surface sites on the exposed faces, in situ FTIR spectra of adsorbed CO as probe molecule have been carried out. It was shown that the sulfidation steps are affecting not only the structure of MoS2 nanosheets, including their curvature, surface defects, and stacking order, but are involving the support, too, and then in turn the MoS2/support interaction, so helping to control and preserve the size of the particles. Lastly, to elucidate the nature of the hybrid composites, a simple scheme summarizing the reaction pathways has been proposed.