EVIDENCE FOR THE POTASSIUM-PROMOTED ACTIVATION OF METHANE ON A K-DOPED NIO/NI(100) SURFACE

The formation and reactivity of multilayer NiO films, both with and without added potassium, have been investigated using high-resolution electron-energy-loss spectroscopy, low-energy electron diffraction, and x-ray photoelectron spectroscopy. We have found a strong interaction between K and NiO, as evidence by the formation of K-O bonds, by a high-temperature potassium thermal-desorption peak and by an activated rate of NiO formation on K/Ni(100). We have also investigated the reactivities of the K-doped NiO surface toward CH4 and H-2 by monitoring the removal rate of oxygen from the surface. Our results demonstrate that the presence of K significantly enhances the reactivity of NiO with CH4, while the presence of K does not increase the reactivity of NiO toward H-2.