Adsorption of H 2 , O 2 , H 2 O, OH and H on monolayer MoS 2

Hydrogen and hydrogen-containing gases are commonly used as reductants in chemical vapor deposition growth of MoS 2 . Here, we consider the defects resulting from the presence of hydrogen during growth and the resulting electronically active defects. In particular, we find that the interstitial hydrogen defect is a negative- U center with amphoteric donor and acceptor properties. Additionally, we consider the effects of interaction with water and oxygen. The defects are analysed using density functional theory calculations.