Resolving active species during the carbon monoxide oxidation over Pt(111) on the microsecond timescale

Area of Science:

• Surface Science
• Catalysis
• Chemical Kinetics

Background:

• Traditional catalytic studies use steady-state conditions, averaging data and masking short-lived intermediates.
• This averaging can lead to misinterpretations of catalyst function and active species.
• Time-resolved ambient pressure X-ray photoelectron spectroscopy (tr-APXPS) offers microsecond resolution under reaction conditions.

Purpose of the Study:

• To investigate the oxidation of carbon monoxide (CO) over platinum (Pt(111)) using tr-APXPS.
• To differentiate between active and spectator species during catalysis.
• To elucidate the mechanism of CO oxidation on Pt(111).

Main Methods:

• Utilizing time-resolved ambient pressure X-ray photoelectron spectroscopy (tr-APXPS).
• Conducting catalytic studies under reaction conditions with microsecond time resolution.
• Employing CO pulsing techniques to identify active species.

Main Results:

• Identified chemisorbed oxygen as the primary reacting species with CO for CO2 formation.
• Demonstrated that Pt surface oxide is not the main reactive species in this reaction.
• Supported a primary Langmuir-Hinshelwood mechanism for CO oxidation over Pt(111).

Conclusions:

• Chemisorbed oxygen plays a crucial role in CO oxidation over Pt(111), resolving a long-standing debate.
• tr-APXPS provides critical insights into transient intermediates in catalytic reactions.
• Dynamic catalyst operation through parameter tuning can enhance reaction product formation.