A DFT Study of NO Reduction Promoted by Gold ...

While nanoscale gold particles show exceptional catalytic activity towards NO reduction, not much is known about the detailed reaction mechanism and the influence of charge state of Au nanoparticles on the reactivity. We here report a systematic theoretical study by carrying out density functional theory calculations for NO reduction promoted by Au4+ and Au4, which represent two simplest prototypes of Au nanoparticles with different charge states. In all cases, it is found that the catalytic cycle proceeds via the complexes of Au-H with NO and involves two sequential elementary steps: the rupture of the H-H bond in H2 and the formation of H2O and N2O molecule. The calculated results show that the cationic cluster is generally more active than the neutral cluster, indicating that the activity of Au cluster towards NO reduction is attributable to the concentration of positive charges on the cluster. The present theoretical study rationalizes the early experimental findings well and enriches our understanding of the reduction of NO on the Au cluster.