Abstract

Acetone adsorbed on rutile TiO₂ nanoparticles was investigated with respect to its energetic, vibrational, and chemical properties. Temperature-dependent ultrahigh-vacuum Fourier transform infrared spectroscopy measurements for different acetone dosages (4.5–900 L) give insights into the acetone adsorption behavior. Those experiments indicate thermal-induced reactions of acetone on rutile TiO₂ surfaces yielding new species. Density functional theory calculations were performed to investigate acetone adsorption on rutile TiO₂(110). Particularly, the importance of sampling the adsorption configuration space is shown. Adsorption geometries that are energetically significantly more favorable than the commonly used high-symmetry configurations are presented. To facilitate the comparability to the experiment, theoretical infrared spectra were computed using density functional perturbation theory for various acetone adsorption geometries using different exchange-correlation functionals. Additionally, computational spectra were obtained for several species which are potential products from reactions of acetone on TiO₂ surfaces. The investigated species are η²-acetate, η²-diolate, η¹-enolate, and mesityl oxide. For η¹-acetone, experimental and calculated spectra fit well for low temperatures, whereas for elevated temperatures, emerging bands indicate the formation of diolate.

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