Oxide-supported precious metals are among the most widely used industrial catalysts. Significant efforts have been placed into developing synthetic protocols to reduce the metal nanoparticle size due to their expense. At the limit of these efforts is the deposition of single precious metal atoms on supports. Due to challenges associated with the synthesis and characterization of single precious metal atoms on oxide supports, understanding of the potential reactivity of dispersed metal atoms on oxide supports remains a contentious topic. Here we will present a detailed analysis of the adsorption and oxidation reactivity of CO on single Pt atoms, sub-nanometer Pt oxide clusters, and sub-nanometer metallic Pt clusters on anatase TiO2. Control over the structure and oxidation state of the Pt species was achieved on very high surface area (290 m2/g) TiO2 supports through variations in weight loadings, deposition pH, and liquid volume during solution based synthesis. Characterization of the structures was achieved through a correlated probe molecule IR and scanning transmission electron microscopy (STEM) analysis. Through this approach we were able to rigorously differentiate the spectroscopic signatures of CO bound to each type of Pt structure and demonstrate that the steady state CO oxidation reactivity decreases in the order of isolated Pt/TiO2 &gt; metallic Pt clusters/TiO2 &gt;&gt; oxidized Pt clusters/TiO2. More generally, the approach highlighted in this work is expected to be generally applicable for characterizing the potential unique reactivity of isolated precious metal atoms on oxide supports.<br/>

Spectroscopic signatures and reactivity of CO adsorbed to Pt atoms, Pt oxide clusters, and metallic Pt clusters on anatase TiO<sub>2</sub>

254th National Meeting (2017)

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Spectroscopic signatures and reactivity of CO adsorbed to Pt atoms, Pt oxide clusters, and metallic Pt clusters on anatase TiO2

Spectroscopic signatures and reactivity of CO adsorbed to Pt atoms, Pt oxide clusters, and metallic Pt clusters on anatase TiO₂