| AVS 57th International Symposium & Exhibition | |
| Surface Science | Monday Sessions |
| Session SS1-MoM |
| Session: | Reactivity and Selectivity on Catalytic Surfaces |
| Presenter: | J.F. Weaver, University of Florida |
| Authors: | J.F. Weaver, University of Florida C. Hakanoglu, University of Florida J.A. Hinojosa, Jr., University of Florida A. Antony, University of Florida J.M. Hawkins, University of Florida A. Asthagiri, University of Florida |
| Correspondent: | Click to Email |
The formation of palladium oxide (PdO) is thought to be responsible for the exceptional activity of supported Pd catalysts toward the complete oxidation of alkanes under oxygen-rich conditions. In this talk, I will discuss our recent investigations of the adsorption and activation of n-alkanes on a PdO(101) thin film that is prepared by oxidizing Pd(111) in ultrahigh vacuum (UHV) using an oxygen atom beam. We find that alkanes adsorb relatively strongly on the PdO(101) surface by forming σ-complexes along the rows of coordinatively unsaturated Pd atoms. The formation of σ-complexes causes the alkane binding energies on PdO(101) to exceed those of alkanes physisorbed on Pd(111). We also find that the alkane σ-complexes on PdO(101) act as precursors for initial C-H bond cleavage; propane and n-butane undergo facile C-H bond cleavage below about 215 K in UHV. Finally, I will discuss density functional theory calculations which show that dative bonding between the alkane and cus-Pd atoms weakens the coordinated C-H bonds, thereby lowering energy barriers for C-H bond scission by as much as 100 kJ/mol. These findings provide insights for understanding the role of molecularly chemisorbed precursors in the initial activation of alkanes on PdO(101) and possibly other transition-metal oxide surfaces.