Adsorption and reactivity of nitric oxide on Co(0001)

LEED, Auger spectroscopy and thermal desorption have been used to study NO chemisorption and the NO/CO reaction on Co(0001). NO is adsorbed dissociatively at room temperature, with unit sticking probability and a (√39 R16.1° × √39 R′16.1°) structure is formed. At high coverages the adsorption becomes molecular. Desorption of N 2 follows apparent 1st order kinetics from an N + O layer, and fractional order kinetics from a pure N layer; a lateral interaction model with N-N near neighbour attractions, small N-O near neighbour attraction and O-O near neighbour repulsions explains both the apparent desorption kinetics and the change from dissociative to molecular adsorption. The zero coverage desorption energies of N 2 and NO are measured as ∼220 and ∼94 kJ mol −1 respectively. The reaction between NO and CO closely resembled that between O 2 and CO on this surface and it is concluded that both follow a Langmuir-Hinshelwood mechanism.