Displacement reaction of CO by NO on the Ni(111) surface

Co-adsorption states and thermal stability of NO + CO on Ni(111) were investigated using infrared reflection absorption spectroscopy and temperature programed desorption. The mechanism for the displacement of CO by NO was clarified. Co-adsorbed NO induced hollow-to-ontop site-conversion of CO; NO molecules occupied hollow sites. Ontop and two hollow CO species were observed in the co-adsorbed phase. The ontop and lower frequency hollow CO were assigned to CO neighboring hollow NO; higher frequency hollow CO were assigned to CO forming those domain. The hollow-to-ontop site-conversion of CO occurred due to local interactions between CO and NO, which destabilized the CO by 0.5 eV. This destabilization afforded facile displacement of CO by NO at 300 K.