CO dissociation and CO2 formation catalysed by Na atoms adsorbed on Ni(1 1 1)

The co-adsorption of CO and Na on Ni(1 1 1) was investigated by High-Resolution-Electron Energy-Loss-Spectroscopy. The measurements were performed both at room temperature and at 160 K and for several Na coverages, from a sub-monolayer to almost two monolayers. At room temperature the CO molecules dissociate above a critical Na coverage. Unexpectedly, the CO dissociation takes place also at 160 K. Low Na coverages induce a direct CO–CO reaction, whose products, CO2 molecules and C atoms, remain adsorbed on the Ni surface at low temperature.