Adsorption, desorption and surface reactions of CO and NO on Pd{320} (original) (raw)

Adsorption, desorption and a surface reaction between coadsorbed CO and NO on a stepped Pd{320} (Pd(S)[3(110)×(100)]) surface have been studied using molecular beam surface scattering (MBSS ), temperature-programmed desorption/reaction (TPD/TPR) and X-ray photoelectron spectroscopy ( XPS). CO adsorbs molecularly on Pd{320} with an initial sticking probability close to unity at 300 K, and reversibly desorbs upon heating according to the first-order desorption kinetics. NO adsorption on Pd{320} is molecular in the temperature range of 300-400 K as indicated by MBSS and XPS. NO desorbs molecularly in addition to the formation of relatively large amounts of N 2 and N 2 O near 500 K. Coadsorbed NO and CO are observed to react upon heating to produce an extremely narrow TPR peak of CO 2 at~470 K. The location and half-width of the CO 2 TPR peak are almost independent of the initial coverages of CO and NO, which indicates an autocatalytic behaviour of the NO-CO reaction kinetics on Pd{320}.