Direct Observation of Transition Metal Dichalcogenides in Liquid with Scanning Tunneling Microscopy

We present atomic-resolution images of TiSe_2, MoTe_2 and TaS_2 single crystals in liquid condition using our home-built scanning tunneling microscopy (STM). By facilely cleaving of single crystals in liquid, we were able to keep the fresh surface not oxidized within a few hours. Using the high-stable home-built STM, we have obtained atomic resolution images of TiSe_2 accompanied with the single atom defects as well as the triangle defects in solution for the first time. Besides, the superstructure of MoTe_2 and hexagonal charge-density wave domain structure in nearly commensurate phase of TaS_2 were also obtained at room temperature (295 K). Our results provide a more efficient method in investigating the lively surface of transition metal dichalcogenides. Besides, the high stable liquid-phase STM will support the further investigations in liquid-phase catalysis or electrochemistry.