Ideal, Defective, and Gold--Promoted Rutile TiO2(110) Surfaces: Structures, Energies, Dynamics, and Thermodynamics from PBE+U

Abstract

Extensive first principles calculations are carried out to investigate gold-promoted TiO2(110) surfaces in terms of structure optimizations, electronic structure analyses, ab initio thermodynamics calculations of surface phase diagrams, and ab initio molecular dynamics simulations. All computations rely on density functional theory in the generalized gradient approximation (PBE) and account for on-site Coulomb interactions via inclusion of a Hubbard correction, PBE+U, where U is computed from linear response theory. This approach is validated by investigating the interaction between TiO2(110) surfaces and typical probe species (H, H2O, CO). Relaxed structures and binding energies are compared to both data from the literature and plain PBE results. The main focus of the study is on the properties of gold-promoted titania surfaces and their interactions with CO. Both PBE+U and PBE optimized structures of Au adatoms adsorbed on stoichiometric and reduced TiO2 surfaces are computed, along with their electronic structure. The charge rearrangement induced by the adsorbates at the metal/oxide contact are also analyzed and discussed. By performing PBE+U ab initio molecular dynamics simulations, it is demonstrated that the diffusion of Au adatoms on the stoichiometric surface is highly anisotropic. The metal atoms migrate either along the top of the bridging oxygen rows, or around the area between these rows, from one bridging position to the next along the [001] direction. Approximate ab initio thermodynamics predicts that under O-rich conditions, structures obtained by substituting a Ti5c atom with an Au atom are thermodynamically stable over a wide range of temperatures and pressures.

20 pages, 12 figures, accepted for publication in Phys. Rev. B

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• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• A linear response approach to the calculation of the effective interaction parameters in the LDA+U method
• Density functional theory in transition-metal chemistry: a self-consistent Hubbard U approach
• Composition, structure, and stability of the rutile TiO_2(110) surface: oxygen depletion, hydroxylation, hydrogen migration and water adsorption
• Charge Localization Dynamics induced by Oxygen Vacancies on the Titania TiO${}_2$(110) Surface
• Adsorption and Diffusion of Pt and Au on the Stoichiometric and Reduced TiO2 Rutile (110) Surfaces

Cited by in corpus (4)

• Interplay between adsorbates and polarons: CO on rutile TiO${}_2$(110)
• Transition Metal Atoms Pathways on Rutile TiO2 (110) Surface: Distribution of Ti3+ States and Evidence of Enhanced Peripheral Charge Accumulation
• On the Impact of Solvation on a Au/TiO2 Nanocatalyst in Contact with Water
• Controlling Projection-Space Artifacts in DFT+U via Projection-Consistent U_{eff}