The adsorption and oxidation of cyanogen on copper surfaces

The adsorption of cyanogen on clean and oxygen pre-treated graphite supported copper films, and a polycrystalline copper surface, and the co-adsorption of cyanogen and oxygen on graphite supported copper films, and a polycrystalline copper surface has been studied using X-ray photoelectron spectroscopy. Cyanogen dissociates on the copper surfaces at 300 K, yielding an adsorbed cyano group, CN(a). On the oxygen pre-treated copper surface cyanogen reacts quantitatively with the adsorbed oxygen at 300 K to form a surface cyanate species, NCO. On annealing to 600 K this species decomposes, leaving only N adatoms and residual adsorbed CN on the surface. The co-adsorption of cyanogen and oxygen from a cyanogen–oxygen mixture enhances the formation of NCO to the extent that all available surface oxygen is consumed to form NCO on annealing at 450 K. In the absence of available atomic surface oxygen NCO does not decompose at temperatures up to 600 K. NCO and NCO2 are shown to be the intermediates in the oxidation of cyanogen on copper films and a polycrystalline copper foil.