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Consecutive H2 Oxidation Mediated by Au2VO4+ Clusters

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journal contribution
posted on 22.04.2016, 00:00 by Xiao-Hong Zhou, Zi-Yu Li, Tong-Mei Ma, Sheng-Gui He
Laser-ablation generated gold–vanadium oxide cluster cations Au2VOx+ (x = 3, 4) were mass-selected by a quadrupole mass filter and interacted with H2 in an ion trap reactor. The reactions were characterized by mass spectrometry and density functional theory calculations. The Au2VO4+ cluster can oxidize two H2 molecules consecutively to produce Au2VO3+ and then Au2VO2+, the latter of which can react with one O2 molecule to regenerate Au2VO4+. Therefore, a catalytic cycle for H2 oxidation by O2 mediated with the Au2VO2+ clusters can be proposed. The theoretical studies predict that the gold atoms in both Au2VO4+ and Au2VO3+ are the active adsorption sites and facilitate the heterolytic cleavage of H2 in collaboration with the separate O2– ions of the vanadium oxide support. The consecutively oxidative reactivity of Au2VO4+ is attributed to the activation and dissociation of the superoxide or peroxide species (O2•– or O22–) into two reactive atomic oxygen species (O2–) with the promotional effect of gold atoms acting as electron donors. This study provides molecular-level insights into the elementary mechanisms of the H2 catalytic oxidation on the surface.