Abstracts Book - IMRC 2018

• SD1-O025
GLOBAL OPTIMIZATION OF BIMETALLIC PtCu CLUSTERS
SUPPORTED ON CeO2(111)
Lauro Oliver Paz Borbón 1 , Ignacio L. Garzón 2 , Alvaro Posada Amarillas 3
1 Instituto de Física - Universidad Nacional Autónoma de México, Chemical Physics, Mexico.
2 Instituto de Física - Universidad Nacional Autónoma de México, Complex Systems, Mexico.
3 Universidad de Sonora, DIFUS, Mexico.
One of the most technologically relevant application of oxide supported
transition metals lies in heterogeneous catalysis [1]. One example are emission
control systems, such as the automobile three-way catalytic converter. One
component of the catalytic converter is Pt/CeO 2 ; where Pt serves to oxidize
hydrocarbons and carbon monoxide, while ceria (CeO 2 ) acts as an oxygen
storage component. Another example are Cu particles supported over a variety
of ceria surfaces, which have been recently used as a catalyst for hydrogen
production via partial oxidation of methanol (POM) [2]. Although in both cases,
control at the nm-scale is desirable to open new technological possibilities, there
is still limited knowledge at the more fundamental, sub-nanometer level - both
experimentally and theoretically - regarding the structure and stability of monoand
bimetallic (Pt, Cu) clusters over ceria surfaces.
In this talk, I will describe the implementation of an unbiased Density Functional
Theory based global optimization Basin Hopping Monte Carlo algorithm (BH-
DFT) to study growth trends of Pt, Cu and PtCu clusters up to 5 atoms in size,
across all the composition range [3,4]. From our results, we observe a clear
preference for planar 2D structures. Our calculations show the reducibility of
CeO 2 (111) provides a mechanism to anchor the metal clusters where they
become oxidized in a two-way charge transfer mechanism: (a) an oxidation
process, where O surface atoms withdraw charge the metal atoms forming metal-
O surface bonds, and (b) surface Ce 4+ atoms are reduced to Ce 3+ . In this way, active
role of CeO 2 (111) support in modifying the structural properties and eventual
chemical reactivity of sub-nanometer mono and bimetallic clusters is
computationally demonstrated.
References: [1] Freund, H.-J.; et al. Phys. Chem. Chem. Phys., 16, 8148 (2014) [2]
Araiza, D.G.; et al., Catal. Sci. Technol., 7, 5224 (2017) [3] Paz-Borbón, L.O.; et al.,
Phys. Chem. Chem. Phys.,19, 17845 (2017) [4] Paz- Borbón, L.O.; Garzón, I.L.;
Posada-Amarillas, A.; In preparation (2018)