Ni-CeO2 is a highly efficient, stable and non-expensive catalyst for methane dry reforming at relative low temperatures (700 K). The active phase of the catalyst consists of small nanoparticles of nickel dispersed on partially reduced ceria. Experiments of ambient pressure XPS indicate that methane dissociates on Ni/CeO2 at temperatures as low as 300 K, generating CHx and COx species on the surface of the catalyst. Strong metal-support interactions activate Ni for the dissociation of methane. The results of density-functional calculations show a drop in the effective barrier for methane activation from 0.9 eV on Ni(111) to only 0.15 eV on Ni/CeO2-x (111). At 700 K, under methane dry reforming conditions, no signals for adsorbed CHx or C species are detected in the C 1s XPS region. The reforming of methane proceeds in a clean and efficient way.

The results of core-level photoemission indicate that Ni-CeO 2 (111) surfaces with small or medium coverages of nickel are able to activate methane at 300 K producing adsorbed CH x and CO x (x = 2,3) groups. Calculations based on density-functional 1 theory predict relatively low activation energy of 0.6−0.7 eV for the cleavage of the first C−H bond in the adsorbed methane molecule. Ni and O centers of ceria work in a cooperative way in the dissociation of the C−H bond at room temperature where a low Ni loading is crucial for the catalyst activity and stability. The strong electronic perturbations in the Ni nanoparticles produced by the ceria support of varying nature such as stoichiometric and reduced, result in a drastic change in their chemical properties towards methane adsorption and dissociation as well as the DRM reaction. The coverage of Ni had a drastic effect on the ability of the system to dissociate methane and catalyze the dry reforming process.