Ligand induced structure and property changes of 1T-MoS2

Stabilizing metastable 1T-MoS2 sheets is significant for their potential applications. In this work, we investigate the influence of surface adsorption of a series of functional groups (including –H, –O, –SH, –NH2, –CH3, –CF3, –SCH3 and –OCH3) on the structural and electronic properties of 1T-MoS2 by using first-principles calculations. Strong adsorptions of these functional groups eventually transform 1T-related MoS2 monolayers into the 1T′ phase (featuring zigzag Mo–Mo chains). The adsorptions of functional groups on 1T′-MoS2 monolayers highly prefer half of the surface sites (the St sites) and try to form adsorbate pairs at the St sites of the second nearest neighbors, which means that the study of surface-decorated 1T′-MoS2 monolayers should not be based on randomly generated configurations. Factors like the type of functional group as well as its coverage and configurations make the relationship between the structure of the adsorbate–MoS2 complex and its electronic properties (e.g. band gap) unclear, which implies that the band gap engineering through surface adsorption is unpredictable.