Probing Catalytic Sites and Adsorbate Spillover on Ultrathin FeO2–x Film on Ir(111) during CO Oxidation

• Published in: ACS nano 2024-03, Vol.18 (9), p.7114-7122
• Main Authors: Yin, Hao, Yan, Yu-Wei, Fang, Wei, Brune, Harald
• Format: Article
• Language: English
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/acsnano.3c11400

The spatially resolved identification of active sites on the heterogeneous catalyst surface is an essential step toward directly visualizing a catalytic reaction with atomic scale. To date, ferrous centers on platinum group metals have shown promising potential for low-temperature CO catalytic oxidation, but the temporal and spatial distribution of active sites during the reaction and how molecular-scale structures develop at the interface are not fully understood. Here, we studied the catalytic CO oxidation and the effect of co-adsorbed hydrogen on the FeO2–x /Ir­(111) surface. Combining scanning tunneling microscopy (STM), isotope-labeled pulse reaction measurements, and DFT calculations, we identified both FeO2/Ir and FeO2/FeO sites as active sites with different reactivity. The trilayer O–Fe–O structure with its Moiré pattern can be fully recovered after O2 exposure, where molecular O2 dissociates at the FeO/Ir interface. Additionally, as a competitor, dissociated hydrogen migrates onto the oxide film with the formation of surface hydroxyl and water clusters down to 150 K.