Synthesis of TiS2 Nanobelts

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Description: Background: Layered titanium dichalcogenides (i.e. TiX2 where X=S, Se, Te) are representative members of an extended family of two-dimensional (2D) metal dichalcogenides that exhibit anisotropic physical properties. These anisotropies arise from strong, covalent M—X intralayer bonding motifs in contrast to the weak van der Waals bonding between layers. Both the layered structure and the anisotropy of interatomic bonds make it possible to create different low dimensional systems (such as, fullerene-like nanoparticles, nanotubes, nanodisks, nanobelts etc...) as well as intercalation and thermoelectric materials whose electronic properties vary substantially depending on the presence of atomic defects in their bulk or surface layers. In recent years, there has been a resurgence of interest in TiS2 as a nanostructured material. This is because its reduced dimensionality causes changes in its physical and chemical properties. As an example, bulk TiS2 is a semi-metal whereas nanostructured TiS2 is a narrow-gap semiconductor whose band gap (Eg) should appear in the visible. Namely, theoretical calculations predict that Eg can be tuned by changing TiS2s size and shape, yielding values ranging from 1.25 eV for nanotubes to 1 .65 eV for thin sheet-like morphologies. This, in conjunction with their favorable electron affinities, makes TiS2 nanostructures interesting for potential photocatalytic hydrogen generation applications. TiS2 nanostructures are also attractive precursors for the synthesis of nanostructured oxy-sulfides, TiS2-xOx, with tunable spectral responses in the visible. In addition,TiS2 could be a potentially interesting material for use in lithium ion battery applications due to its large Li storage capacity and open sheet-like morphologies that improve ion incorporation/extraction kinetics.   Technology: We have discovered a facile solution chemistry approach by which to produce high quality TiS2 nanobelts. Resulting TiS2 nanostructures have thin belt-like morphologies with average lengths between 400-500 nm and with widths between 10-25 nm. An estimated thickness is 2-5 nm. The produced TiS2 nanobelts have an apparent absorption in the visible between 580 nm and 610 nm, which suggests semiconducting behavior. Preliminary photocorrosion studies in water show that they are stable with no evidence of degradation after 24 hours under white light illumination. The facile production of titanium sulfide nanoparticles will enable its use in photocatalytic hyrdogen production and Li ion batteries.