CO dissociation on K-modified Cu(112) and Cu(117)

Using valence band photoelectron spectroscopy it is demonstrated that CO dissociates on the potassium-modified stepped copper surfaces, Cu(1 1 2) and Cu(1 1 7). The dissociation process is conditioned by both the presence of steps and an alkali metal coverage above a certain threshold value. Carbonate is formed at 375 K via the process CO + CO --> CO2 + C and reaction with oxygen. Further heating to 600 K results in decomposition of the carbonate. The threshold alkali metal coverage for dissociation of CO on stepped copper surfaces depends on the step density. It is found that the height of the Fermi edge in the valence band photoelectron spectra is correlated with the CO uptake for a given potassium coverage and the perturbation and dissociation of the CO molecule with increasing temperature. (C) 2001 Elsevier Science B.V. All rights reserved.