Local reaction rates and surface diffusion on nanolithographically prepared model catalysts: experiments and...

Area of Science:

• Surface science
• Heterogeneous catalysis
• Chemical kinetics

Background:

• CO oxidation on supported metal catalysts is crucial for industrial applications.
• Understanding nanoparticle behavior is key to designing efficient catalysts.
• Model catalysts allow precise control over experimental variables.

Purpose of the Study:

• To investigate the angular distribution of desorbing products during CO oxidation on a Pd/silica model catalyst.
• To explore reactant diffusion, shadowing, and backscattering effects on catalyst nanoparticles.
• To develop a reaction-diffusion model for quantitative analysis of surface reaction rates.

Main Methods:

• Utilized molecular beam methods and angular resolved mass spectrometry.
• Prepared model catalysts with controlled particle size, position, and aspect ratio using electron beam lithography.
• Characterized catalysts using atomic force microscopy and scanning electron microscopy.
• Investigated both oxygen-rich and CO-rich reaction regimes.

Main Results:

• Developed a reaction-diffusion model that quantitatively describes experimental data.
• Gained insights into local reaction rates on catalyst nanoparticle surfaces.
• Determined temperature and reactant flux dependent effects on CO oxidation.
• Obtained information on oxygen surface mobility under steady-state conditions.

Conclusions:

• The developed model accurately describes CO oxidation on Pd/silica nanoparticles.
• The study provides a detailed understanding of reaction dynamics and surface mobility.
• This approach enables quantitative analysis of catalyst performance and optimization.