Platinum‐Iron(II) Oxide Sites Directly Responsible for Preferential Carbon Monoxide Oxidation at Ambient Temperature: An Operando X‐ray Absorption Spectroscopy Study**
Ilia I. Sadykov, Vitaly L. Sushkevich, Frank Krumeich, Rob Jeremiah G. Nuguid, Jeroen A. van Bokhoven, Maarten Nachtegaal, Оlga V. Safonova
Abstract
Abstract Operando X‐ray absorption spectroscopy identified that the concentration of Fe 2+ species in the working state‐of‐the‐art Pt−FeO x catalysts quantitatively correlates to their preferential carbon monoxide oxidation steady‐state reaction rate at ambient temperature. Deactivation of such catalysts with time on stream originates from irreversible oxidation of active Fe 2+ sites. The active Fe 2+ species are presumably Fe +2 O −2 clusters in contact with platinum nanoparticles; they coexist with spectator trivalent oxidic iron (Fe 3+ ) and metallic iron (Fe 0 ) partially alloyed with platinum. The concentration of active sites and, therefore, the catalyst activity strongly depends on the pretreatment conditions. Fe 2+ is the resting state of the active sites in the preferential carbon monoxide oxidation cycle.