  We employ density functional theory (DFT) to investigate the adsorption and
dehydrogenation of methane on the BNG-Ir13 cluster at both low and high oxygen
coverage. The DFT calculations show that the low-oxygen-coverage BNG-Ir13
cluster (BNG-Ir13O cluster) forms methanol and formaldehyde with a lower
activation energy barrier compared to the high-oxygen-coverage BNG Ir13
cluster. Furthermore, the results reveal that the BNG-Ir13 cluster with low
oxygen coverage has a higher methane adsorption energy and a lower activation
energy barrier for methane dissociation compared to the high-oxygen-coverage
BNG-Ir13 cluster. Quantitatively, the methane adsorption energy on the
low-oxygen-coverage BNG-Ir13 cluster is -0.44 eV, and the second
dehydrogenation of methane is the rate-determining step with an energy barrier
of 1.24 eV, in both cases lower numbers than those observed for the
high-oxygen-coverage BNG-Ir13 cluster.
