Distinctions between Supported Au and Pt Catalysts for CO Oxidation: Insights from DFT Study

Distinctions between supported Au and Pt catalysts on TiO 2 (110) for CO oxidation have been investigated by means of density functional theory calculations. Our study shows that the following factors determine the obvious differences between two kinds of catalysts for CO oxidation: (1) The adsorption strength of Au 11 is much weaker than that of Pt 11 on TiO 2 (110), but both are strongly dependent on the surface properties of TiO 2 . The addition of Pt increases the interaction between the alloyed cluster and TiO 2 support. (2) O 2 can adsorb only on the interfacial site between Au and TiO 2 (110), whereas O 2 can adsorb on both the interfacial and metal sites of supported Pt nanoparticles. (3) CO is directly activated by the adsorbed molecular oxygen on the interfacial site of Au 11 /TiO 2 (110) _OH . While on Pt 11 /TiO 2 (110) _OH, the main reaction pathway is the dissociated oxygen reacting with CO. Once a Pt ensemble is formed on Au clusters (such as Au 8 Pt 3 /TiO 2 (110) _OH ), both of the reaction mechanisms work.