Pre-protection strategy performed in processable aqueous dispersions of TiS ₂ nanosheets to fabricate laminar films with improved electric properties

Abstract Processable aqueous dispersions of two-dimensional (2D) transition metal dichalcogenides (TMDs) nanosheets show extraordinary promise in assembling laminar films for a variety of applications but are usually limited by the oxidation of adsorbed water molecular on the edge and defect regions, which damage the stability of the colloidal solution and electric properties of the resulted films. In this work, we developed a pre-protection strategy by adding ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) as the protective agent into TiS ₂ nanosheets aqueous dispersions. The introduction of EDTA-2Na can effectively slow down the adsorption and decomposition of confined water molecules and enhance the oxidation resistance of TiS ₂ nanosheets in the colloidal solution. Compared with the untreated TiS ₂ nanosheets, the storage time of the pre-protected nanosheets in aqueous dispersions can be significantly improved, and the electrical conductivity of prepared laminar films as thermoelectric materials also increased from 2.43 × 10 ³ S m ⁻¹ to 1.51 × 10 ⁴ S m ⁻¹ . Our exploration provides a new concept performed in aqueous solution for the protection of TMDs nanosheets, which can be adopted to fabricate TMDs films with stable electric properties by controlling the assembly process of colloidal chemistry