The scope of this work is to study at atomistic
level the mechanism of hydrogen spillover promoted by metal
particles on oxide surfaces. By means of Density Functional
Theory calculations with Hubbard correction (DFT+U) we
have analyzed the adsorption and dissociation of molecular
hydrogen on anatase titania, a-TiO2 (101), and tetragonal
zirconia, t-ZrO2 (101), surfaces in the presence of a supported
Ru10 nanocluster. The role of the supported metal particle is
essential as it favors the spontaneous dissociation of H2, a
process which does not occur on the bare oxide surface. At low
hydrogen coverage, the H atoms prefer to stay on the Ru10
particle, charge accumulates on the metal cluster, and reduction of the oxide does not take place. On a hydroxylated surface, the
presence of a Ru nanoparticle is expected to promote the reverse effect, i.e. hydrogen reverse spillover from the oxide to the
supported metal. It is only at high hydrogen coverage, resulting in the adsorption of several H2 molecules on the metal cluster,
that it becomes thermodynamically favorable to have hydrogen transfer from the metal to the O sites of the oxide surface. In both
TiO2 and ZrO2 surfaces the migration of an H atom from the Ru cluster to the surface is accompanied by an electron transfer to
the empty states of the support with reduction of the oxide surface
The scope of this work is to study at atomisticlevel the mechanism of hydrogen spillover promoted by metalparticles on oxide surfaces. By means of Density FunctionalTheory calculations with Hubbard correction (DFT+U) wehave analyzed the adsorption and dissociation of molecularhydrogen on anatase titania, a-TiO2 (101), and tetragonalzirconia, t-ZrO2 (101), surfaces in the presence of a supportedRu10 nanocluster. The role of the supported metal particle isessential as it favors the spontaneous dissociation of H2, aprocess which does not occur on the bare oxide surface. At lowhydrogen coverage, the H atoms prefer to stay on the Ru10particle, charge accumulates on the metal cluster, and reduction of the oxide does not take place. On a hydroxylated surface, thepresence of a Ru nanoparticle is expected to promote the reverse effect, i.e. hydrogen reverse spillover from the oxide to thesupported metal. It is only at high hydrogen coverage, resulting in the adsorption of several H2 molecules on the metal cluster,that it becomes thermodynamically favorable to have hydrogen transfer from the metal to the O sites of the oxide surface. In bothTiO2 and ZrO2 surfaces the migration of an H atom from the Ru cluster to the surface is accompanied by an electron transfer tothe empty states of the support with reduction of the oxide surface
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