In Situ DRIFTS Study of Single-Atom, 2D, and 3D Pt on γ -Al 2 O 3 Nanoflakes and Nanowires for C 2 H 4 Oxidation.

Up to now, a great number of catalysts have been reported that are active in the oxidation of volatile organic compounds (VOCs). However, supported noble-metal catalysts (especially Pt-based catalysts) are still the most excellent ones for this reaction. In this study, Pt species supported on γ-Al₂O₃ and ranging from single-atom sites to clusters (less than 1 nm) and 1–2 nm nanoparticles were prepared and investigated for oxidizing C₂H₄. The Pt-loaded γ-Al₂O₃ nanoflakes (PtAl-NF) and Pt-loaded γ-Al₂O₃ nanowires (PtAl-NW) were successfully prepared. The samples were characterized using XRD, TEM, XPS, HAADF-STEM, and in situ DRIFTS. Based on in situ DRIFTS, a simple surface reaction mechanism was developed. The stable intermediates CO on single-atom Pt, subnanometer Pt particles, and fully exposed Pt clusters could be explained by the strong binding of CO molecule poisoning Pt sites. Moreover, the oxidation of C₂H₄ was best achieved by Pt particles that were 1–2 nm in size and the catalytic activity of PtAl-NF was better when it had less Pt. Lastly, the most exposed (110) facets of γ-Al₂O₃ nanoflakes were more resistant to water than the majorly exposed (100) facets of γ-Al₂O₃ nanowires. [ABSTRACT FROM AUTHOR]