O2 activation at the Au/MgO(001) interface boundary facilitates CO oxidation.

Density functional theory calculations reveal that the work function of Au supported on MgO(001) is substantially reduced because of an interfacial dipole moment formed at the Au/MgO interface. Consequently, the Au/MgO interface plays an active role in the activation of O2 molecules by promoting charge transfer to the O2 2π* orbital. The presence of F-centers in the MgO substrate can further promote the charge transfer and bonding of O2 at the interface boundary. However, O2 dissociation is kinetically hindered. The system is then able to catalyze CO oxidation at low temperature as adsorbed CO and O2 readily react to form CO2 with a low energy barrier.