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

Distinctions between supported Au and Pt catalysts on TiO2(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 Au11 is much weaker than that of Pt11 on TiO2(110), but both are strongly dependent on the surface properties of TiO2. The addition of Pt increases the interaction between the alloyed cluster and TiO2 support. (2) O2 can adsorb only on the interfacial site between Au and TiO2(110), whereas O2 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 Au11/TiO2(110)_OH. While on Pt11/TiO2(110)_OH, the main reaction pathway is the dissociated oxygen reacting with CO. Once a Pt ensemble is formed on Au clusters (such as Au8Pt3/TiO2(110)_OH), both of the reaction mechanisms work.