Interaction of CO and O2 with supported Pt single-atoms on TiO2(110)

Abstract

In view of the high activity of Pt single atoms in the low-temperature oxidation of CO, we investigate the adsorption behavior of Pt single atoms on reduced rutile TiO2(110) surface and their interaction with CO and O2 molecules using scanning tunneling microscopy and density function theory calculations. Pt single atoms were prepared on the TiO2(110) surface at 80 K, showing their preferred adsorption sites at the oxygen vacancies. We characterized the adsorption configurations of CO and O2 molecules separately to the TiO2-supported Pt single atom samples at 80 K. It is found that the Pt single atoms tend to capture one CO to form Pt-CO complexes, with the CO molecule bonding to the fivefold coordinated Ti (Ti5c) atom at the next nearest neighbor site. After annealing the sample from 80 K to 100 K, CO molecules may diffuse, forming another type of complexes, Pt-(CO)2. For O2 adsorption, each Pt single atom may also capture one O2 molecule, forming Pt-O2 complexes with O2 molecule bonding to either the nearest or the next nearest neighboring Ti5c sites. Our study provides the single-molecule-level knowledge of the interaction of CO and O2 with Pt single atoms, which represent the important initial states of the reaction between CO and O2.