Adsorption and Vibrations of α,β-Unsaturated Aldehydes on Pure Pt and Pt−Sn Alloy (111) Surfaces I. Prenal

Abstract

The adsorption and thermal decomposition of the α,β-unsaturated aldehyde prenal (3-methyl-2-butenal) have been studied on Pt(111), the Pt3Sn/Pt(111) and Pt2Sn/Pt(111) surface alloys, and the corresponding terminations of the Pt3Sn(111) bulk alloy by means of high-resolution electron energy loss spectroscopy (HREELS), temperature-programmed desorption (TPD), and low-energy electron diffraction (LEED). By comparing the experimental results with extensive theoretical calculations of the multitude of possible adsorption configurations of prenal using density functional theory (DFT), the adsorption configurations actually present on all model catalysts have been identified. This approach, thus, reveals a new way to identify complex, multifunctional molecules adsorbed on model catalyst surfaces. On Pt(111), prenal is strongly adsorbed and decomposes at approximately 300 K. By the aid of density functional theory (DFT), five flat-lying adsorption structures of η2, η3, and η4 hapticity, which exhibit similar adso...