O2 Activation over Ag-Decorated CeO2(111) and TiO2(110) Surfaces: A Theoretical Comparative Investigation

Luca Brugnoli,Frédéric Labat,Alfonso Pedone,Carlo Adamo,Maria Cristina Menziani

doi:10.1021/acs.jpcc.0c09080

Abstract

Periodic spin-polarized hybrid density functional theory calculations have been performed to investigate the reactivity of pristine, O-defective, and Ag-decorated CeO2(111) and TiO2(110) surfaces w...

Highlights

Transition-metal nanoparticles (NPs) dispersed over metaloxide supports constitute one of the main types of heterogeneous catalysts, with countless applications in many industrial and technological processes for the abatement of environmental pollutants produced by industrial activity and motor vehicles.[1−3] In particular, catalysts based on silver NPs supported at the oxide surfaces are appealing for their high activity in low-temperature oxidation processes[4−11] and their remarkable lower costs with respect to those based on gold and platinum, making them more suitable for large-scale applications.[7,12]
Spin-polarized density functional theory (DFT) calculations have been performed with the ab initio CRYSTAL17 package,[51] adopting the global hybrid PBE052 functional with atom-cantered basis set constituted by Gaussian type functions
Periodic spin-polarized hybrid DFT calculations have been carried out to characterize the adsorption of an Ag10 cluster on TiO2(110) and CeO2(111) surfaces, the formation of surface oxygen vacancies along with the adsorption and dissociation of O2 on the different surfaces considered

Summary

INTRODUCTION

Transition-metal nanoparticles (NPs) dispersed over metaloxide supports constitute one of the main types of heterogeneous catalysts, with countless applications in many industrial and technological processes for the abatement of environmental pollutants produced by industrial activity and motor vehicles.[1−3] In particular, catalysts based on silver NPs supported at the oxide surfaces are appealing for their high activity in low-temperature oxidation processes[4−11] and their remarkable lower costs with respect to those based on gold and platinum, making them more suitable for large-scale applications.[7,12] It is known that the catalytic activity toward the oxidation of silver NPs supported on reducible oxides is enhanced[13] by the metal-support interaction effects which boost the reactivity of both the support and metal.[5,14,15] Among the reducible oxides, ceria (CeO2) and titania (TiO2) have been the most investigated ones in catalysis.[16]. Two mechanisms have been proposed to explain the oxidation activity of these systems: one involves the release of O from the oxide lattice (Mars-van Kravelen, MvK) and the other involves the production of oxygenated species as peroxide (O22−), superoxide (*O2−), or atomic oxygen (O or *O−), when O2 molecules interact with reactive sites (oxygen vacancy, oxide/metal junction, or metal particle surface) on the catalyst surfaces. These highly reactive oxygenated species react with the co-adsorbed substrate. The interaction with O2 has been investigated for both silver-free and silver-decorated surfaces, highlighting the role of VO and considering two pathways corresponding to the formation of the peroxo and superoxo species

COMPUTATIONAL DETAILS

RESULTS AND DISCUSSION

CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES