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Recently, it has been shown that model catalysts consisting of cerium oxide nanoparticles supported on noble metal surfaces are very convenient to clarify the reaction mechanism of important industrial reactions such as water–gas shift, CO oxidation, and methanol synthesis from CO2. Moreover, these special inverse catalysts are highly active, even more than the regular metal/oxide catalyst in some cases. However, there is a lack of fundamental knowledge about the electronic nature of the supported CeOx nanoparticles (NPs) and their interaction with the noble metal support. In this work we have carried out DFT calculations on CeOx/Cu(111), CeOx/Ag(111), and CeOx/Au(111) interfaces for both supported particles and periodic 2D film. The most stable and most reduced CeOx NPs are found when supported on Cu(111), followed by Ag(111) and Au(111). A similar behavior is observed for periodic 2D CeO2(111) films supported on the M(111) surfaces, although the reducibility is lower and the stability higher in extended...

During the photochemical reaction of organic molecules on oxide surfaces, radicals are formed and participate in heterogeneous photocatalytic processes; however, understanding the mechanistic origins and the fate of such species under reaction conditions is difficult. In this work we carry out a combined experimental and theoretical study on the thermal and photochemical interaction of ethanol with RuOx/TiO2(110) surfaces. Ethanol dissociatively adsorbs on both TiO2 and RuOx/TiO2 surfaces forming ethoxide. Our DFT calculations indicate that the ethoxide formation is more exothermic on RuOx/TiO2(110) surfaces (ΔE= −1.61 eV) than on the clean rutile TiO2(110) surface (ΔE= −0.95 eV). Defect sites present on RuOx/TiO2 surfaces can dissociate part of the ethoxide to acetaldehyde even below 300 K, which can be further oxidized to acetate resulting in the reduction of the RuOx nanoparticles. Exposure to UV irradiation of the ethoxide covered surfaces in the presence of oxygen at 300 K resulted in considerable de...

Recently, there has been a strong interest in understanding the role of mixed-metal oxides in catalysts used for the production of hydrogen through the splitting of water. Here, we investigate the structural and chemical properties of RuOx/TiO2(110) surfaces employing scanning tunneling microscopy, photoemission, and density functional calculations. Ruthenium oxide forms unique wirelike structures on top of TiO2(110) which are very reactive toward water dissociation, being able to cleave O–H bonds at a temperature as low as 200 K. The calculated barrier for the dissociation of water on RuO2 nanowires is

Density functional theory (DFT) calculations combined with surface thermodynamic arguments and the Gibbs-Curie-Wulff equilibrium morphology formalism have been employed to explore the effect of the reaction conditions, temperature (T), and gas-phase partial pressures (p h2 and p h2s ) on the stability of low Miller index ruthenium sulfide (RuS 2 ) surfaces. The calculated thermodynamic surface stabilities and the resulting equilibrium morphology models suggest that unsupported RuS 2 nanoparticles in HDS conditions are like to a polyhedron with six, eight, and twelve (100), (111), and (102) faces, respectively. The area of these faces covers about 40%, 37%, and 23% of the total particle, respectively. The atomic basins of the outermost individual atoms of the exposed surfaces were determined using the quantum theory of atoms in molecules methodology. Direct visualization of these basins has shown that a hole just at the middle of the outermost sulfur basins provides access to uncovered metal sites. Analysis of the electrostatic potential mapped onto a selected electron density isocontour (0.001 au) on the exposed surface reveals a very high potential reactivity of these holes toward electrodonating reagents. Consequently, the high attraction between these uncovered sites and S atoms coming from reagent polluting molecules makes these kinds of particles quite active for HDS catalysis.