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tex2html_wrap_inline32 Atomistic Simulation Group, School of Mathematics and Physics, Queen's University, Belfast BT7 1NN, U.K. tex2html_wrap_inline34 School of Chemistry, Queen's University, Belfast BT9 5AG, U.K.

CO oxidation on Pt(111): An Ab Initio Density Functional Theory Study

Ali Alavi tex2html_wrap_inline32 , Peijun Hu tex2html_wrap_inline34

November 16, 1998

Abstract:

CO oxidation on Pt(111) is studied with ab initio density functional theory, using plane-waves and pseudopotentials. The low energy pathway and transition state for the reaction CO/ tex2html_wrap_inline40 -O/Pt(111) tex2html_wrap_inline42 CO tex2html_wrap_inline44 /Pt(111) are identified using a constrained minimisation scheme. ( Snaphots of the reaction pathway can be downloaded from gif. See also [1]). The transition state consists of the O atom at a bridge site, and the CO molecule at a neighbouring top site, with C-O separation of 2.1Å. The activation energy tex2html_wrap_inline46 eV. Approximately 60% of this energy can be accounted for by the O atom moving from the hollow to bridge site ( thereby breaking a O-metal bond), while the remainder is due mainly to placing a CO atom at a top site adjacent to the bridging O atom. The pathway can be rationalised in terms of competition of the O and C atoms for bonding with the underlying surface. It is suggested that the physical origin of the predominant barrier is the strength of the O-metal bond, and modification of this bond strength can be expected to affect crucially the catalytic activity.





Ali Alavi
Mon Nov 16 16:59:03 GMT 1998

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