CO oxidation onAu∕TiOx∕Mo{112}: Structure characterization and catalytic activity studied usingab initiocalculations

Abstract

Low-temperature CO oxidation over Au/oxides attracts alot of interest for its industrial and scientific importance. To date, it remains controversial where it occurs. Recently, Chen and Goodman suggested the reaction can occur on Au itself from their experiment of CO oxidation over $\mathrm{Au}∕\mathrm{Ti}{\mathrm{O}}_{x}∕\mathrm{Mo}{112}$. Here, using ab initio thermodynamic calculations we determined the chemical stoichiometry of the $\mathrm{Ti}{\mathrm{O}}_{x}$ film as $\mathrm{Ti}{\mathrm{O}}_{3}$ and resolved the geometrical structure of the $\mathrm{Ti}{\mathrm{O}}_{3}$ and the subsequent Au films. The segregation is revealed to be favored upon Au deposition/annealing on the $\mathrm{Ti}{\mathrm{O}}_{3}∕\mathrm{Mo}{112}$. The interface between Au and $\mathrm{Ti}{\mathrm{O}}_{3}$ that is supported on Mo{112} is identified as the only reaction site. The superior reactivity of a ``two-layer Au film'' is then rationalized.