Design of active catalysts from first principles: concepts, examples, and perspectives
Prof Gianfranco Pacchioni
The role of electronic structure theory in the rationalization of catalytic processes on solid surfaces and in the design of new catalysts has grown continuously over the past 20 years. The two fundamental approaches to the solution of the Schrödinger equation, based on wave function determination (e.g. Hartree-Fock and post-Hartree-Fock) or based on electron density determination (density functional theory, DFT) have been applied to the problem, both with advantages and limitations. Particular important is the identification of proper descriptors in catalytic reactions, and the derivation of general concepts from theoretical studies. As specific example of simulations in heterogeneous catalysis we will consider the case of metal/oxide interfaces. Nanoparticles deposited on an oxide support, or nanostructured oxides grown on a metal surface may result in new efficient catalysts. We will discuss in particular the high reactivity of the oxygen atoms at the boundary region between a metal cluster and the oxide surface in CO oxidation, a prototype reaction. Au nanoparticles on TiO2 and ZrO2 supports will be used to provide compelling evidence that the reaction occurs at specific sites of the Au/oxide interface and that even a non-reducible oxide such as ZrO2 can become reducible when interfaced with gold. Also, the deposition of oxide ultrathin films on metals may result in completely different properties of deposited metal clusters, and recent examples of this effect will be discussed for ultrathin ZnO layers on Cu.
Examples of successful stories as well as cases of complete failures in predicting catalytic mechanisms from first principles will be addressed, in order to provide a coherent picture of the present status of theoretical simulations of heterogeneous catalysis.
- A. Ruiz Puigdollers, P. Schlexer, S. Tosoni, G. Pacchioni, “Increasing oxide reducibility: the role of metal/oxide interfaces in the formation of oxygen vacancies”, ACS Catalysis, 7, 6493 (2017).
- A. Ruiz-Puigdollers, G. Pacchioni, “CO oxidation on Au nanoparticles supported on ZrO2: role of metal/oxide interface and oxide reducibility”, ChemCatChem, 9, 1119 (2017).
- S. Tosoni, C. Li, P. Schlexer, G. Pacchioni, “CO adsorption on graphite-like ZnO bilayers supported on Cu(111), Ag(111) and Au(111) surfaces”, J. of Physical Chemistry C, 121, 27453 (2017).
- H. Thang, S. Tosoni, G. Pacchioni, “Evidence of charge transfer to atomic and molecular adsorbates on graphitic-like ZnO/X(111) (X = Cu, Ag, Au) ultrathin films”, submitted.