Surface and Interface Reactivity of Au Nanoparticles Supported on Rutile-TiO₂(110) toward H₂O, O₂, CO, and CO₂

Au nanoparticles with different coverages were deposited on a reduced rutile-TiO2(110) [r-TiO2(110)] surface. Their structure and reactivity were probed with adsorption and reaction of H2O, O2, CO, and CO2 using X-ray photoelectron spectroscopy and temperature programmed desorption spectra. Au nanoparticles nucleate on bridge-bonded oxygen (BBO) vacancies of the r-TiO2(110) surface and quench the adsorption of probing molecules on the BBO vacancies. Water facilely dissociates at the Au–TiO2 interface of Au/r-TiO2(110) to subsequently produce H2 above 200 K but not on the r-TiO2(110) surface. The observed oxygen species on r-TiO2(110) and Au/r-TiO2(110) surfaces do not react with coadsorbed CO whereas hydroxyl groups at the Au–TiO2 interface of Au/r-TiO2(110) react with coadsorbed CO to produce CO2. Both the BBO vacancies and the Au–TiO2 interface play vital roles in this reaction. These results greatly help to fundamentally understand the structure of Au/TiO2 catalysts and their catalytic activity in the reactions involving H2O, O2, CO, and CO2.