Facile Synthesis of Large and Thin TiS2 Sheets via a Gas/Molten Salt Interface Reaction

Highly crystalline hexagonal titanium disulfide (TiS 2 ) sheets were synthesized at the gas/liquid interface between TiCl 4 vapor and the dissolved Na 2 S in equimolar NaCl–KCl melts at temperatures between 700°C and 850°C. TiS 2 sheets with sizes of about 10–20 μm and thicknesses of about 50–200 nm have been collected at 700°C–750°C, and much bigger (50–100 μm in sizes) and thicker (1–5 μm in thickness) TiS 2 sheets were obtained at 850°C. The mass transfer preferential growth of an interphase layer and the thermodynamically preferential enlargement of the (001) plane of the hexagonal TiS 2 crystal were thought to have led the formation of large and thin TiS 2 sheets in this proposed gas/liquid interface process. Due to the density difference, the ripe TiS 2 sheets sank into the melt allowing the continuing preparation of TiS 2 sheets. These TiS 2 sheets could spontaneously assemble to TiS 2 membranes or be ultrasonically exfoliated to few-layer TiS 2 sheets with thicknesses less than 5 nm. The presented approach should be potentially extendable to the synthesis of large and thin sheets of other layered metal dichalcogenides in large scale.