Operando detection of single nanoparticle activity dynamics inside a model pore catalyst material

Area of Science:

• Catalysis
• Nanotechnology
• Surface Science

Background:

• Nanoconfinement in porous catalysts can create reactant concentration gradients due to local conversion.
• These gradients lead to inefficient use of active catalyst materials, with some parts becoming inactive.
• Studying these effects experimentally is challenging due to material complexity and the need for high spatial resolution.

Purpose of the Study:

• To develop a method for visualizing reactant concentration gradients within model porous catalysts at the single-particle level.
• To investigate how these gradients affect the oxidation state and activity of downstream catalyst particles under operando conditions.
• To establish a framework for understanding single-particle catalysis in gas-phase reactions.

Main Methods:

• Fabrication of quasi-two-dimensional mimics of porous catalysts.
• Integration of nanofluidics with single-particle plasmonics.
• Online mass spectrometry for real-time analysis.
• Operando single-particle resolution during CO oxidation on a Copper (Cu) model catalyst.

Main Results:

• Direct visualization of reactant concentration gradient formation on single Cu nanoparticles within a model pore.
• Demonstration that these gradients dynamically control the oxidation state of downstream particles.
• Correlation between particle oxidation state and catalytic activity was established.

Conclusions:

• Single-particle approaches are crucial for understanding complex catalyst materials and reaction mechanisms.
• The developed methodology provides a general framework for studying gas-phase single-particle catalysis.
• Understanding and mitigating concentration gradients is key to optimizing catalyst performance and material utilization.