Tuning metal clusters properties: the important role of the support

When metal nanoparticles are deposited on the surface of an oxide support, or when a nanostructured oxide, either a nanoparticle or a thin film, is grown on a metal, completely new and unexpected phenomena may occur. We refer in particular to the high reactivity of the oxygen atoms at the boundary region between a metal cluster in contact with an oxide surface; these atoms can be removed from interface sites at much lower cost than in other regions of the surface, thus altering completely the reactivity of the heterogeneous catalyst. At the cluster/oxide interface reducibility may differ completely from that of the bulk material or of its surface. The atomistic study of CO oxidation on Au nanoparticles deposited on TiO₂ and ZrO₂ surfaces is used as an example to provide compelling evidence that the reaction occurs at specific sites at the Au/oxide interface and that even a non-reducible oxide such as ZrO₂ can become reducible when nano-structured or interfaced with a metal. Also depositing oxide ultrathin films on metals may result in completely different properties of deposited metal clusters. Recent examples of this effect are discussed for thin layers of ZrO₂ and ZnO.

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[2] A. Ruiz-Puigdollers, G. Pacchioni, “CO oxidation on Au nanoparticles supported on ZrO₂: role of metal/oxide interface and oxide reducibility”, ChemCatChem, 9, 1119-1127 (2017).
[3] A. Ruiz-Puigdollers, G. Pacchioni, “Reducibility of ZrO₂/Pt₃Zr and ZrO₂/Pt 2D films compared to bulk zirconia: a DFT+U study of oxygen removal and H₂ Adsorption”, Nanoscale, 9, 6866-6876 (2017).