Liquid-phase exfoliation of titanium disulfide nanosheets in aqueous ionic liquid solutions for highly efficient CO2 electroreduction

Titanium disulfide nanosheets (TiS2 NSs) have attracted considerable research interest due to their eco-friendliness and outstanding electrical transport properties. However, the large scale preparation of TiS2 NSs usually is plagued by the employ of poisonous solvents and low production. Herein, we develop a green, highly efficient and scalable tactic to exfoliate bulk TiS2 powders in aqueous ionic liquids solutions under ambient conditions. This result shows that the exfoliation yield can reach 57.6 %, which surpasses the most values for the liquid-phase exfoliation of TiS2 reported in literatures. The thickness of TiS2 NSs is mainly in the range of 1 nm to 2 nm, and the lateral dimension is up to a few hundreds of nanometers. The molecular geometry and anionic alkalinity of the ionic liquids play key roles in the delamination and stability of TiS2 NSs. In addition, TiS2 NSs have been used as catalysts in the electrocatalytic CO2 to CO conversion with the faradaic efficiency of 68.7 %, which is six times that by the bulk TiS2 powder. Thus, the liquid phase delamination approach reported in this work has a great potential in manufacturing 2D layer materials for high activity electrocatalysis.