A combined in-situ XAS–DRIFTS study unraveling adsorbate induced changes on the Pt nanoparticle structure

• New in-situ XAS–DRIFTS cell design for improved background correction.
• Adsorbate induced reversible changes in the structure of Platinum nanoparticles.
• Reoxidation of Platinum nanoparticles due to strong metal support interaction.
• atop bonded CO is the only binding geometry under high CO concentration.

The adsorption behavior of Platinum nanoparticles was studied for the as-received catalyst (under inert gas), under hydrogen and CO atmosphere using our newly designed in-situ cell. X-ray Absorption Spectroscopy (XAS) and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) experiments were performed simultaneously with high data quality. Structural information and the type of adsorbate could be revealed via Extended X-ray Absorption Fine Structure (EXAFS) analysis, Δμ X-ray Absorption Near Edge Structure analysis (Δμ XANES) and in-situ DRIFTS. The as-received catalyst showed sub-surface oxygen and O(n-fold). Under CO atmosphere only CO(atop) was found. Reversible adsorbate induced changes of the Pt nanoparticle structure were derived from changes in the PtPt coordination number and the corresponding bond distance. Under reducing conditions (H2, CO) a significant increase in both values occurred. Temperature dependent desorption of CO revealed a gradual shift from PtCO to PtO. Reoxidation was clearly assigned to strong metal support interaction from the SiO2 support.

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