Adsorption and dissociation of O2 on MoSe2 and MoTe2 monolayers: ab initio study

Adsorption and dissociation of O-2 molecule on the MoSe2 and MoTe2 monolayers are studied by using density functional theory (DFT) within the generalized gradient approximation (GGA) and a supercell approach. The physisorbed O-2 molecule on MoSe2 and MoTe2 with a magnetic moment (MM) close to that for an isolated O-2 molecule has small adsorption energy and long distance from the surface. The dissociative adsorption of configuration R5(R6) is the most stable adsorption site, whereas the chemisorption of O-2 is unfavorable at all adsorption sites. The dissociative adsorption of configuration R4 induces dramatic changes of electronic structures and localized spin polarization both for monolayer MoSe2 and MoTe2. The analysis of electronic density of states (DOSs) shows that the contribution of spin polarization is mainly from the hybridization between O-p, Se(Te)-p and Mo-d orbitals.