Adsorption and dissociation of O2 on MoO2(1[combining macron]11) surfaces: a DFT study
Quan Zhang1, Minhua Zhang, Tomasz Wiltowski
1Department of Mechanical Engineering and Energy Processes, Southern Illinois University, Carbondale, IL 62901, USA.
Abstract:
The adsorption and dissociation of O2 on MoO2(1[combining macron]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.
