DFT study on complete ethylene decomposition on flat and stepped Pd

We applied density functional theory (DFT) calculations to study ethylidyne (CCH3) adsorption and decomposition to C and H over flat and stepped Pd surfaces. Our calculations show that ethylidyne is the most stable molecule among all the possible dehydrogenation or decomposition residues of ethylene. We discuss various possible reaction pathways for ethylidyne decomposition and point out that the most probable one is via ethynyl (CCH) species suggested also by experimental observations. Our calculations indicate that the presence of steps modify the potential energy surface by increasing the binding of most of the species, and also lowering the activation barrier for several reactions. Furthermore we show that the energetics related to dehydrogenation of ethylene and its derivatives manifest a Bronsted-Evans-Polanyi type of behavior. (C) 2010 Elsevier B.V. All rights reserved.