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 adsorption energies E
ads between −47 and −59 kJ/mol, have
been identified on the surface. The adsorption energy of prenal on the considered Pt−Sn alloys is significantly
weaker. On the Pt3Sn and the Pt2Sn/Pt(111) surface alloys, the HREEL spectra recorded at 170 K are essentially
assigned to two vertical η-top-(s)-trans configurations (E
ads = −39.1 and −30.8 kJ/mol on Pt3Sn and −33.4
kJ/mol on Pt2Sn) adsorbed atop the protruding Sn atoms. Due to the weak adsorption of these structures, the
vibrational frequencies are only slightly perturbed as compared to their corresponding gas-phase values. The
primary role of tin is a general weakening of the adsorption of prenal on the alloy surfaces. While on Pt(111),
flat adsorption configurations are preferred, alloying with tin induces a drastic change in the adsorption
geometries to vertical η1-top forms. On the alloy surfaces, generally an oxygen−tin interaction is required to
form competitive adsorption structures at all, whereas a coordination from the aldehydic function to a Pt is
hardly stable.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.