Mechanisms for CO oxidation on Fe(iii)-OH-Pt interface: a DFT study.

Area of Science:

• Surface science and catalysis
• Computational chemistry and materials science

Background:

• Carbon monoxide (CO) oxidation is a critical reaction in catalysis.
• Iron-hydroxide supported on platinum (Fe(OH)(x)/Pt) nanoparticles are potential catalysts.
• Understanding the catalytic cycle and structure-activity relationships is essential.

Purpose of the Study:

• To investigate the full catalytic cycle of CO oxidation on Fe(OH)(x)/Pt nanoparticles.
• To explore the role of different structural models and surface sites.
• To elucidate the mechanism of CO oxidation and identify rate-limiting steps.

Main Methods:

• Periodic density functional calculations were employed.
• Three structural models of Fe(OH)(x)/Pt nanoparticles were simulated: Fe(OH)(x)/Pt(111), Fe(OH)(x)/Pt(332), and Fe(OH)(x)/Pt(322).
• The reaction pathways for CO oxidation were analyzed.

Main Results:

• Fe(iii)-OH-Pt stepped sites were found to readily oxidize adsorbed CO to CO2.
• These stepped sites simultaneously generate coordinatively unsaturated iron sites, facilitating O2 activation.
• Interfacial vacancies on Fe(OH)(x)/Pt(111) preferentially adsorb CO over O2, inhibiting the catalytic cycle.

Conclusions:

• The catalytic activity of Fe(OH)(x)/Pt nanoparticles is highly structure-sensitive.
• Stepped sites are identified as active centers for CO oxidation.
• The strength of Fe(iii)-OH bonds influences the observed structure sensitivity.