The interaction of hydrogen, ethylene and their mixtures with a commercial Pd black was studied. Hydrogen treatment at 300 K created a rather clean Pd surface with some residual carbon. Ethylene introduced in high hydrogen excess exerted hardly any influence on the metallic properties of Pd, as shown by X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS). The carbon content did not change. Contacting Pd with ethylene in low excess of H2 or without any hydrogen changed the Pd 3d line, indicating its chemical interaction with C. Simultaneously, a new component appeared in the C 1s region at BE ∼ 283.5 eV. It indicated the formation of Pd-C bonds, responsible for changes in the Pd valence state. Intensity drop at the near-Fermi edge region in UPS corroborated this interaction. Pd also underwent considerable structural rearrangement, as shown by the appearance of a large peak in the UP spectra at ∼8 eV, corresponding to the enrichment of the sodium carbonate impurity on the surface. This component proved to be a good indicator of surface flexibility.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry