Au/TiO₂-Catalyzed Benzyl Alcohol Oxidation on Morphologically Precise Anatase Nanoparticles

Area of Science:

• Heterogeneous Catalysis
• Materials Science
• Nanotechnology

Background:

• Gold nanoparticles (Au NPs) supported on titanium dioxide (TiO2) are effective catalysts for selective oxidation reactions using molecular oxygen.
• The morphology and exposed facets of the TiO2 support can influence the catalytic performance of supported Au NPs.

Purpose of the Study:

• To investigate the impact of TiO2 support morphology on the catalytic activity of Au/TiO2 catalysts for aerobic oxidation reactions.
• To understand the relationship between support facet exposure ({001} vs. {101}) and the size and distribution of Au nanoparticles.

Main Methods:

• Preparation of two distinct TiO2 anatase supports: nanoplatelets ({001} facet) and truncated bipyramids ({101} facet) via nonaqueous solvothermal synthesis.
• Deposition of Au nanoparticles using the deposition-precipitation method.
• Characterization using DRIFTS, XPS, TEM, and STEM to analyze support morphology and Au NP size.
• Catalytic testing of aerobic oxidation of benzyl alcohol and trifluoromethylbenzyl alcohol.

Main Results:

• Smaller Au nanoparticles were observed on the TiO2 support with predominantly exposed {101} facets.
• The Au/TiO2 catalyst utilizing the {101}-faceted support exhibited higher reaction rates in the aerobic oxidation of alcohols.
• Increased catalytic activity was attributed to a larger Au/TiO2 interface area resulting from smaller Au NPs on the {101} support.
• Hammett slope analysis indicated no significant electronic differences between Au NPs on the different supports, suggesting geometric effects dominate.

Conclusions:

• Support morphology is a critical factor in tuning the catalytic performance of Au/TiO2 catalysts.
• The {101} facet exposure of TiO2 anatase supports leads to enhanced catalytic activity due to smaller Au nanoparticle formation and increased interfacial area.
• Geometric effects, rather than electronic effects, are the primary drivers for the observed differences in catalytic activity.