Strong Metal-Support Interactions between Pt Single Atoms and TiO₂

Area of Science:

• Heterogeneous catalysis
• Materials science
• Surface chemistry

Background:

• Strong metal-support interaction (SMSI) is crucial in heterogeneous catalysis.
• The occurrence of SMSI in single-atom catalysts is not well understood.

Purpose of the Study:

• To investigate if single-atom catalysts can exhibit SMSI.
• To elucidate the mechanism of SMSI in single-atom systems.
• To understand the role of SMSI in defining active sites for catalysis.

Main Methods:

• High-temperature reduction of TiO2-supported Pt single atoms and nanoparticles.
• Characterization of SMSI effects on Pt single atoms.
• CO adsorption studies to probe electronic and structural changes.
• Catalytic testing for 3-nitrostyrene hydrogenation.

Main Results:

• SMSI was observed in TiO2-supported Pt single atoms at higher temperatures than for Pt nanoparticles.
• SMSI-affected single atoms are not covered or submerged by the support.
• CO adsorption suppression is due to coordination saturation (18-electron rule), not physical encapsulation.
• Single atoms are the primary active sites for 3-nitrostyrene hydrogenation, with encapsulated nanoparticles showing minimal activity.

Conclusions:

• Single-atom catalysts can exhibit SMSI, distinct from nanoparticle behavior.
• Coordination saturation, not physical blocking, explains suppressed adsorption on SMSI single atoms.
• SMSI provides a method to tune single-atom catalysts and identify active sites in reactions like 3-nitrostyrene hydrogenation.