Long-term aging of CVD grown 2D-MoS 2 nanosheets in ambient environment

A chemically vapor deposited MoS 2 nanosheets (NSs) is aged in the laboratory at ambient and at 40% average humidity for ~36 months. Nanorods of few microns in length and few nanometers in diameter are found to grow from the MoS 2 seeds. They have been growing as a result of the chemical reaction between the MoS 2 NSs and ambient O 2 and moisture, they exhibit an amorphous phase structure in the stoichiometric form of MoO 3 . Density functional theory simulations further reveal the role of H 2 O and O 2 in the transformation of the MoS 2 NSs. The adsorption energy of O 2 molecules on the MoS 2 sites is E ad = −1.09 eV as compared to lowest absolute E ad = −0.10 eV of H 2 O indicating the favorable adsorption of O 2 and subsequent Mo oxidation. This study provides valuable insight into the aging phenomenon of MoS 2 exposed to O 2 and moisture which might limit their application.