Tailoring surface morphology on anatase TiO₂ supported Au nanoclusters: implications for O₂ activation

Area of Science:

• Surface Science
• Computational Chemistry
• Materials Science

Background:

• The interface between metal clusters and support surfaces is key for catalytic activity.
• Understanding molecule activation at these interfaces is vital for catalyst design.

Purpose of the Study:

• To model and investigate oxygen molecule adsorption and activation on anatase titanium dioxide (TiO2) surfaces with and without gold (Au) nanoclusters.
• To explore the role of surface defects (oxygen vacancies) and morphology (steps) in O2 activation.
• To determine how manipulating Au nanocluster orientation influences O2 adsorption and activation.

Main Methods:

• Plane-wave Density Functional Theory (DFT) calculations were employed.
• Modeling focused on the anatase TiO2 (101) and (103) surfaces with supported small Au nanoclusters (n=3-5).
• Analysis included adsorption energies, O-O bond lengths, and charge transfer.

Main Results:

• Anatase TiO2 surfaces (101, 103) alone do not activate O2.
• Oxygen vacancies on TiO2 lead to strong O2 adsorption and O-O bond elongation.
• Supported Au nanoclusters significantly enhance O2 adsorption and O-O bond stretching.
• Specific Au cluster orientations at TiO2 step-edges promote O2 activation with a low dissociation barrier.

Conclusions:

• The interface morphology, particularly step-edges, can be exploited to orient Au nanoclusters for efficient O2 activation.
• This approach offers a method for activating O2 at low precious metal loadings.
• Findings have implications for designing supported catalysts for electrocatalytic oxidation reactions.