Z. Paal et al., Interaction of ethylene and hydrogen with a commercial Pd black: carbon accumulation and possible adsorbate-induced rearrangement, PHYS CHEM P, 3(21), 2001, pp. 4644-4649
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 ex
cess exerted hardly any influence on the metallic properties of Pd, as show
n by X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS). The ca
rbon content did not change. Contacting Pd with ethylene in low excess of H
-2 or without any hydrogen changed the Pd 3d line, indicating its chemical
interaction with C. Simultaneously, a new component appeared in the C 1s re
gion at BE similar to 283.5 eV. It indicated the formation of Pd-C bonds, r
esponsible for changes in the Pd valence state. Intensity drop at the near-
Fermi edge region in UPS corroborated this interaction. Pd also underwent c
onsiderable structural rearrangement, as shown by the appearance of a large
peak in the UP spectra at similar to8 eV, corresponding to the enrichment
of the sodium carbonate impurity on the surface. This component proved to b
e a good indicator of surface flexibility.