Two Dimensional Titanium Disulphide Thermoelectric Materials

Abstract

Two dimensional (2D) materials exhibit novel and exciting properties in comparison to their bulk counterparts due to the confinement of charge and heat transport within one plane. 2D materials may also serve as building blocks and can be restacked into composites and superlattices. Potential exists for increasing energy efficiency in renewable energy technologies by exploiting these properties. TiS2 has a natural layered structure allowing it to be exfoliated into 2D layers. It has been found to have a high thermopower and calculations show that the band-gap may be tuneable in the 2D form by varying the 2D layer thickness. 2D TiS2 nanosheet synthesis was explored using liquid exfoliation and direct lithium intercalation exfoliation methods. It was shown that these two methods can both be used to exfoliate bulk TiS2 into thin layered 2D nanosheets. The synthesized particles were characterized using TEM, XRD, SEM, Raman and AFM. The lateral particle sizes synthesized were on the order of a few 100’s of nm in the liquid exfoliation method and a few microns for the direct intercalation exfoliation method. The particle thicknesses obtained from the direct intercalation method were less than 10nm, equivalent to 18 TiS2 monolayers. The major problem encountered in the liquid exfoliation method was poor reproducibility. The advantage of these methods is their simplicity and cost effectiveness. The main disadvantage of these two methods is their lack of fine control over particle thickness.