H<sub>2</sub>O Dissociation at the Perimeter Interface between Gold Nanoparticles and TiO<sub>2</sub> Is Crucial for Oxidation of CO
Tadahiro Fujitani, Isao Nakamura, Atsushi Takahashi
Abstract
To clarify the role of H2O in the oxidation of CO over Au/TiO2 at low temperatures (<320 K), we conducted a temperature-programed desorption analysis of the reactivity of H2O with Au nanoparticles deposited on single-crystal TiO2(110) surfaces. Two desorption peaks were observed: a peak at 370 K was attributed to molecular desorption of H2O, and a peak at 510 K was attributed to recombinative desorption of H2O. The amount of dissociated H2O adsorbed on the Au/TiO2(110) surface increased in inverse proportion to the second power of the mean Au particle diameter in the range of 1–10 nm and increased linearly with increasing perimeter length around the Au particles, indicating that H2O dissociates to H and OH at the perimeter interface between the Au and TiO2. We also found that the H2O dissociation reaction and the oxidation of CO proceeded at the same active sites. We believe that the oxidation of CO is initiated by the dissociation of H2O. The obtained results provide a deeper experimental insight on a role of H2O in the oxidation of CO over Au/TiO2 catalysts.