Adsorption and Reaction of Methyl and Ethyl Iodide on Potassium-Promoted Mo2C/Mo(100) Surface

X-ray photoelectron spectroscopy (XPS) studies revealed that potassium on Mo 2 C/Mo(100) induced cleavage of the C-I bond in adsorbed CH 3 I even at ∼100 K. The temperature of complete C-I bond breaking occurred 60-80 K lower compared to the clean surface. Preadsorbed potassium also influenced the reaction pathway of adsorbed CH 3 formed. It decreased its self-hydrogenation into methane and facilitated the coupling reactions into ethane and ethylene below 200 K. High-resolution electron energy loss spectroscopy (HREELS) confirmed formation of adsorbed CH 3 species and revealed its thermal stability. Potassium exerted a similar influence on the chemistry of C 2 H 5 I on Mo 2 C/Mo(100) surface. Rupture of the C-I bond also occurred more easily on K-covered surface. Ethyl species, the primary product of the dissociation, dehydrogenated into ethylene on one hand and hydrogenated into ethane on the other. Rupture of the C-C bond was not observed even at high potassium coverage. Illumination of coadsorbed layers promoted further dissociation of the C-I bond in both compounds at ∼100 K.