Design of low cost, scalable, and high-performance TiS2 thermoelectric materials via wet ball-milling process

Thermoelectric (TE) materials could provide an efficient means for recovering waste heat energy if a low cost, scalable, and high figure-of-merit material could be fabricated. Here, we report, for the first time, a wet ball-milling method to achieve high-performance two-dimensional (2D) semi-metallic TiS2 nanoplatelets. TiO2 is milled, annealed, and sintered with sulfur under high pressure. The addition of a small amount of sulfur (S) powder during the annealing period prevents sulfur deficiency in the sintered compact, resulting in the formation of a near-stoichiometric TiS2 composition. The formation of 2D TiS2 nanoplatelets was confirmed by X-ray diffraction, field emission scanning electron microscopy with energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. The TE properties were measured in the temperature range of 25-100 degrees C. Further, we obtain that the prepared TiS2 has as high figure of merit as 0.35 at 100 degrees C. Novel wet ball mill processing strategies for the development of highperformance 2D materials such as TiS2 make it possible to incorporate these materials for scaled-up device fabrication.