Laser THz Emission Spectroscopy of Gas Adsorption-Desorption Dynamics in Tungsten Disulfide Nanosheets

摘要

Physically adsorbed gas molecules have dramatic effects on the inherent properties of 2D nanomaterials due to their atomic/molecular-level thinness.In this work, we applied laser THz emission spectroscopy to study the gas adsorption-desorption dynamics of tungsten disulfide (WS_(2)) nanosheets prepared by liquid phase exfoliation technique.We find that in low vacuum conditions, NIR irradiation promotes desorption of O_(2) molecules from WS_(2) nanosheets.Upon exposure to atmospheric air, results suggest slight photo-oxidation caused by NIR irradiation.Strong photo-oxidation by UV illumination is also confirmed, and we also observed subsequent O_(2) desorption from WS_(2) nanosheets by NIR irradiation when the UV illumination is turned off.These results are discussed using the Langmuir adsorption isotherm, which explains the variation of gas adsorption with the gas pressure.