Nanofluidic Trapping of Faceted Colloidal Nanocrystals for Parallel Single-Particle Catalysis

Area of Science:

• Heterogeneous catalysis
• Nanomaterials science
• Surface chemistry

Background:

• Catalyst performance is intrinsically linked to nanoparticle size and shape.
• Understanding structure sensitivity is crucial for designing efficient catalysts.
• Ensemble-averaged measurements obscure single-particle behavior.

Purpose of the Study:

• To investigate the structure sensitivity of catalytic reactions at the single-particle level.
• To correlate nanoparticle shape with catalytic activity for fluorescein reduction.
• To evaluate nanofluidic reactors as a platform for single-catalyst studies.

Main Methods:

• Selective trapping of individual gold (Au) nanocrystals (spherical, cubic, octahedral) in parallel nanofluidic channels.
• Real-time monitoring of fluorescein reduction by sodium borohydride using fluorescence microscopy.
• First-principles calculations to validate experimental findings on reaction mechanisms.

Main Results:

• Distinct structure sensitivity observed for the rate-limiting borohydride oxidation step.
• Catalytic activity varied significantly among spherical, cubic, and octahedral Au nanocrystals.
• Differences attributed to the varying abundance of edge sites on different particle morphologies.

Conclusions:

• Nanoparticle shape is a critical determinant of catalytic activity in borohydride-mediated reactions.
• Nanofluidic reactors enable precise studies of structure-function relationships in catalysis.
• This work highlights the importance of controlling nanoparticle morphology for catalyst optimization.