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

Abstract

Au nanoparticles with different coverages were deposited on a reduced rutile-TiO 2 (110) [r-TiO 2 (110)] surface. Their structure and reactivity were probed with adsorption and reaction of H 2 O, O 2 , CO, and CO 2 using X-ray photoelectron spectroscopy and temperature programmed desorption spectra. Au nanoparticles nucleate on bridge-bonded oxygen (BBO) vacancies of the r-TiO 2 (110) surface and quench the adsorption of probing molecules on the BBO vacancies. Water facilely dissociates at the Au−TiO 2 interface of Au/r-TiO 2 (110) to subsequently produce H 2 above 200 K but not on the r-TiO 2 (110) surface. The observed oxygen species on r-TiO 2 (110) and Au/r-TiO 2 (110) surfaces do not react with coadsorbed CO whereas hydroxyl groups at the Au− TiO 2 interface of Au/r-TiO 2 (110) react with coadsorbed CO to produce CO 2 . Both the BBO vacancies and the Au−TiO 2 interface play vital roles in this reaction. These results greatly help to fundamentally understand the structure of Au/TiO 2 catalysts and their catalytic activity in the reactions involving H 2 O, O 2 , CO, and CO 2 .