Functionalization of monolayer MoS2 with transition metal oxide nanoclusters

The surface functionalization of 2D materials provides the tunability of electronic structure as well as catalytic activity. In this study, we investigate the adsorption of various transition metal dioxide molecules (MO); i.e. TiO2, VO2, CrO2, MnO2, FeO2, CoO2, NiO2, CuO2, ZnO2, on pristine MoS2 monolayer by using firstprinciples spin-polarized density functional calculations. The binding of H2O molecule on MO+MoS2 system is also considered. We observe that MO molecules are adsorbed on MoS2 surface with a slight reduction of the electronic bandgap of bare MoS2. The interactions between the MoS2 surface and molecules can be strong and the formation of chemisorption bonds is possible with binding energies between approximate to 1.2 and approximate to 2.2 eV. MO-adsorbed MoS2 systems are all magnetic except for TiO2, FeO2, and ZnO2 adsorptions. The nonmagnetic ZnO2+MoS2 system displays a strong interaction yielding the largest charge transfer among the systems considered (2.07 e(-)) and the shortest equilibrium bond length between the metal atom and sulphur. However, CuO2+MoS2 is the most stable system energetically with 2.21 eV binding energy. H2O molecule binds only to MoS2+TiO2 structure with very tiny charge transfer from MoS2+TiO2 to H2O, while other systems result in negative binding energy. The results further reveal that metal oxides can be used to alter the electronic and magnetic nature of surfaces, even though weak van der Waals interactions occur between them.