Site-dependent selectivity in oxidation reactions on single Pt nanoparticles

Area of Science:

• Catalysis
• Surface Science
• Nanomaterials

Background:

• Platinum nanoparticles are crucial catalysts in various chemical reactions.
• Understanding site-specific reactivity on nanoparticle surfaces is key to catalyst design.
• N-heterocyclic carbenes (NHCs) are versatile ligands for metal nanoparticles.

Purpose of the Study:

• To investigate site-dependent selectivity in oxidation reactions on platinum nanoparticles.
• To use allyl-functionalized NHCs as molecular probes for surface characterization.
• To correlate reactivity differences with surface atomic structure.

Main Methods:

• Infrared (IR) nanospectroscopy was employed to monitor reactions in situ.
• Allyl-functionalized N-heterocyclic carbenes (allyl-NHCs) were used as probe molecules.
• Oxidation conditions were applied to study reaction pathways.

Main Results:

• Selective oxidation of allyl groups on Pt nanoparticles was observed.
• Allyl groups at the nanoparticle center oxidized to hydroxyl groups.
• Allyl groups at the nanoparticle periphery oxidized to carboxylic acid groups.
• Higher reactivity at the nanoparticle periphery was linked to a greater density of low-coordinated atoms.

Conclusions:

• Site-dependent selectivity in oxidation reactions on Pt nanoparticles is confirmed.
• The periphery of Pt nanoparticles exhibits enhanced reactivity compared to the center.
• Low-coordinated atoms on nanoparticle surfaces play a critical role in catalytic activity.