EventGianfranco Pacchioni

Two-dimensional oxides as new catalytic materials

Two-dimensional oxides grown on a metal represent a new class of materials with unprecedented physical and chemical properties. The geometric and electronic structure of these ultrathin films differ from that of the bulk counterparts [1,2], and the formation of a metal oxide interface generate new effects that have many aspects in common with semiconductor physics. One field where this can be exploited is in the design of new heterogeneous catalysts. For instance, charging of supported nanoparticles on oxide films can be iunduced via direct tunneling from the metal support [3,4]. This effect, which has been demonstrated for the case of gold atoms and clusters, can significantly modify the shape and chemical reactivity of supported metal nanoparticles. Thin oxide films can also become active catalysts thanks to their structural flexibility [5] or nanoporosity. Activation of supported metal clusters can be obtained also by doping an oxide film with transition metal atoms incorporated in the inner layers [6]. Based on our findings, we develop general rules on how to optimize the electron-donor characteristics of oxide thin films and how this can be used to tune the catalytic properties of supported nanoparticles.

[1] L. Giordano, G. Pacchioni, “Oxide films at the nanoscale as new catalytic materials”, Acc. Chem. Res., 44, 1244 (2011).
[2] C. Buchner, S. D. Eder, T. Nesse, D. Kuhness, P. Schlexer, G. Pacchioni, J. R. Manson, M. Heyde, B. Holst, H. J. Freund, “Bending rigidity of 2D silica”, Physical Review Letters, 120, 226101 (2018).
[3] G. Pacchioni, H. J. Freund, “Controlling the charge state of supported nanoparticles in catalysis: lessons from model systems”, Chemical Society Reviews, 47, 8474-8502 (2018).
[4] H. V. Thang, S. Tosoni, G. Pacchioni, “Evidence of charge transfer to atomic and molecular adsorbates on ZnO/X(111) (X = Cu, Ag, Au) ultrathin films. Relevance for Cu/ZnO catalysts.”, ACS Catalysis, 8, 4110-4119 (2018).
[5] Q. Pan, X. Weng, M. Chen, L. Giordano, G. Pacchioni, C. Noguera, J. Goniakowski, S. Shaikhutdinov, H.-J. Freund, “Enahanced CO oxidation on metal/oxide interface: from ultrahigh vacuum to near-atmospheric pressures”, ChemCatChem, 7, 2620-2627 (2015).
[6] F. Stavale, X. Shao, N. Nilius, H.-J. Freund, S. Prada, L. Giordano, G. Pacchioni, “Transition metal dopants and the electron donor characteristic of oxide surfaces”, J. Am. Chem. Soc., 134, 11380 (2012).

oxide thin film

About The Speaker

foto mia 2018

Gianfranco Pacchioni received his PhD at the Freie Universität Berlin in 1984. He worked at the IBM Almaden Research Center, and at the Technical University of Munich. He is Full Professor at the University of Milano Bicocca where he has been Vice Rector for Research (2013-2019) and Director of the Department of Materials Science (2003-2009). He has published more than 500 papers (h index 83; WoS) and given nearly 500 invited talks on the electronic structure of oxide surfaces and interfaces, 2D oxides, defects, supported metal clusters, and catalysis. He received several awards and is Fellow of the Accademia Nazionale dei Lincei (2014), the Academia Europaea (2012), and the European Academy of Sciences (2009). He has authored some popular science books, including “The overproduction of truth”, Oxford University Press, 2018, where he presents a personal view of the problems of contemporary science.