Spatio-temporal pattern formation during CO oxidation on Pt(100) at low and intermediate pressures: A comparative...

Area of Science:

• Surface science
• Chemical kinetics
• Catalysis

Background:

• CO oxidation on platinum surfaces is a model system for studying surface reactions and pattern formation.
• Understanding reaction dynamics across different pressure regimes is crucial for catalysis and bridging the
• pressure-gap

Purpose of the Study:

• To experimentally investigate and compare spatio-temporal pattern formation during CO oxidation on Pt(100) at low (10^-5 mbar) and high (10^-2 mbar) pressures.
• To elucidate the differences in nonlinear phenomena and reaction dynamics between these pressure regimes.

Main Methods:

• Photoemission electron microscopy (PEEM) was used to observe pattern formation at 420–540 K and 10^-5 mbar.
• Ellipsomicroscopy was employed for surface imaging at ~600 K and 10^-2 mbar to bridge the pressure gap.

Main Results:

• Distinct spatio-temporal patterns were observed in the low and high pressure regimes.
• Qualitative and quantitative features of pattern formation and macroscopic reaction rate dynamics differed significantly between the two pressure ranges.
• Subsurface oxygen is proposed as a potential explanation for rate oscillations at higher temperatures.

Conclusions:

• The nonlinear phenomena of CO oxidation on Pt(100) exhibit markedly different characteristics depending on the reactant pressure.
• The findings suggest different underlying mechanisms, potentially involving subsurface oxygen, govern reaction dynamics at varying pressures.