Properties of Isolated and TiO2(110) Supported Pt13 Clusters: A Theoretical Study

MALDONADO, ABEL S.; RAMOS, SUSANA B.; CABEZA, GABRIELA F.

TOPICS IN CATALYSIS

SPRINGER/PLENUM PUBLISHERS

Año: 2019

1022-5528

Metallic subnanoparticles deposited oversupports such as TiO2 play an important role for the design of modelcatalysts for heterogeneous catalysis applications.                Inthis work we study the structure and energetic of Pt13 clusters depositedon TiO2(110)  surfaces, usingan ab initio DFT+U modeling method. We first examine the structural anddynamical stability of the isolated Pt13 nanoclusters by consideringas initial configurations symmetrical Ih and Oh structures and new layeredisomers. We determine their equilibrium geometries, cohesive energies, magneticmoments, electronic and vibrational density of states. The analysis of thevibrational modes reveal that the Oh and Ih structures are dynamically unstableunlike the layered structures that have lower energies. We then examine the Pt13-titaniasystem to characterize the cluster/substrate interaction for both thestoichiometric and reduced surfaces. We characterize different aspects of themetal-oxide interaction by determining their equilibrium geometries, adsorptionenergies, charge transfer effects and electronic density of states. We findthat the Pt13 clustersuffers a strong restructuration when adsorbed on the surface, it deformstowards increasing the interaction of the platinum atoms with the surface,leading to a high value of the adsorption energy and getting oxidized. The Pt13-rutilesystem is semiconductor; for the stoichiometric system a localized state in the band gap is predicted. The calculatedsurface oxygen vacancy formation energy is prefered by the cluster deposition afact that favours the use of this system in the COoxidation reactions from a surface oxygen, an important step in the water gasshift reaction.