The interaction of coadsorbed Cl and CO on Ni(110)

Abstract The influence of preadsorbed chlorine on the adsorption behavior of CO on Ni(110) has been studied using AES, photoemission and work function measurements. It is found that the presence of chlorine causes a drastic reduction of the CO adsorption rate and capacity on the Ni(110) surface. Cl presaturation of the Ni(110) surface completely blocks the CO sticking. Conversely, chlorine displaces preadsorbed CO. At constant total coverage, increasing Cl precoverage causes the 1π level of coadsorbed CO to shift to higher binding energy, while the 5σ level slightly moves towards lower binding energy. These findings together with the decrease in the average dipole moment of CO induced by coadsorbed chlorine indicate the reduced CO-Ni coupling and are in line with the poisonous character of electronegative surface additives in heterogeneous catalysis.