Adsorption and dissociation of O2 on MoO2(11) surfaces: a DFT study

Abstract

The adsorption and dissociation of O₂ on MoO₂(11) surfaces were studied by density functional theory (DFT). The results show that O₂ 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 O₂ 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 O₂ are spin-polarized. The oxygen adsorption shows the ability to reduce the spin of surface Mo atoms. The adsorption energy of the O₂ and O atoms decreases as coverage increases. The transition states of O₂ dissociation were located. The energy barriers for O₂ dissociation on the five-coordinated and four-coordinated Mo top sites are 0.227 eV and 0.281 eV, respectively.