Chemisorption of Trichloroethene on the PdCu Alloy (110) Surface:  A Periodical Density Functional Study

Abstract

In the present work different adsorption modes of trichloroethene on the PdCu alloy have been investigated systematically. With application of ab initio periodic density functional theory, some insights about these adsorption modes have been revealed. The two different (110) terminations of the Cu3Pd alloy have been employed as models for the surface region of the Cu50Pd50 alloy because of Cu segregation. They are based on the regular phase of the face-centered cubic (fcc) structure. The first model shows a mixed (Pd/Cu )1) top layer, whereas the other one is Cu-terminated. The analysis of the position of the center of the d-band projected on the Pd and Cu atoms of both surfaces indicated that the Pd atom in the alloy has similar reactivity to the pure metal surface, whereas the opposite trend has been found for the Cu atoms. This has also been confirmed by the adsorption energy, calculated for the distinct modes. Trichlorethene prefers to interact with the Pd atoms on the mixed PdCu surface. Both di-σ and π modes are the most stable configurations among all studied. On the other hand, the adsorption via the chlorine atoms is the preferred on the Cu-terminated surface. The interaction of the CdC bond of trichloroethene on the Pd atoms is similar to the one of the ethene molecule. The main difference between the adsorption of these two molecules is due to the extra chlorine interactions with the Cu atoms. This allows one to suggest that the di-σ configurations are the precursors of the dissociation reaction on the mixed surface.

Understanding Trichloroethylene Chemisorption to Iron Surfaces Using Density Functional Theory

“…The C-Cl bond elongations of more than 1.5 Å in the iron complexes were much greater than those calculated for TCE chemisorption on Pd alloys (38), but are consistent with those calculated for TCE reactions with an Fe(II) bearing clay mineral, where a maximum elongation of 1.6 Å was observed (39). The greater degree of molecular fragmentation resulting from the chemisorption reaction on iron as compared to noble metals may be attributed to the fact that in addition to catalyzing the reduction reactions, the iron also serves as the electron donor.…”

Design of Pd-based pseudo-binary alloy catalysts for highly active and selective NO reduction

“…The d-band of PdIn was significantly down-shifted below –2.0 eV, because of the hybridization with low energy 4d electrons of In (<–10 eV) 72. On the other hand, PdCu has an intense DOS peak near –1.1 eV derived from Cu,73 which uplifted the d-band center. Pd(In 0.33 Cu 0.67 ) displayed an intermediate DOS diagram due to the contribution of both In and Cu, thus showing a moderate d-band center.…”

Catalytic de-halogenation of alkyl halides by copper surfaces

“…Simulation of catalytic reactions has now been widely deployed to acquire elucidation into experimental measurements [26,27]. Among several tested surfaces, copper represents a potentially effective catalyst owing to its high selectivity toward the occurrence of the dehydrohalogenation reaction leading to the formation of corresponding non-halogenated carbon cuts [28,29]. In this context, copper enjoy some interesting features over other transition metals such as, high natural abundance, and the avoidance of halogen side-products (other than hydrogen halides) [30][31][32].…”