Adsorption and dissociation of O-2 on MoO2((1)over-bar11) surfaces: a DFT study

摘要

The adsorption and dissociation of O-2 on MoO2((1) over bar 11) surfaces were studied by density functional theory (DFT). The results show that O-2 molecules prefer to be adsorbed on the five-coordinated Mo top sites. Density of states analysis shows strong hybridization of Mo 4d orbitals and O 2p orbitals in the Mo-O bond. Clean MoO2 slabs and slabs with O-2 adsorption are metallic conductors, whereas the surface with high O atom coverage is reconstructed and becomes a semiconductor. Surface Mo atoms without adsorbed O or O-2 are spin-polarized. The oxygen adsorption shows the ability to reduce the spin of surface Mo atoms. The adsorption energy of the O-2 and O atoms decreases as coverage increases. The transition states of O-2 dissociation were located. The energy barriers for O-2 dissociation on the five-coordinated and four-coordinated Mo top sites are 0.227 eV and 0.281 eV, respectively.