Effect of TiO2 Crystal Phase and Preparation Method on the Catalytic Performance of Au/TiO2 for CO Oxidation

摘要

Titania-supported gold nanoparticles exhibit excellent low-temperature carbon monoxide (CO) oxidation activity, which is sensitive to the structure of the TiO2 support and the preparation method. In this paper, gold catalysts were prepared on TiO2 with different anatase-to-rutile ratios by the deposition-precipitation method (Au/TiO2-C) and plasma-assisted deposition-precipitation method (Au/TiO2-PC). The highest performance for CO oxidation was obtained over Au/TiO2 for an anatase-to-rutile ratio of 4:6, which may be ascribed to the phase transformation mechanism of TiO2 and the preferential deposition of Au nanoparticles on rutile TiO2 in the deposition-precipitation process. Therefore, enlarged contact surface between the Au nanoparticles and the TiO2 support was obtained, and more oxygen vacancies may be formed, which are beneficial to CO oxidation. Interestingly, compared with Au/TiO2-C, Au/TiO2-PC exhibited enhanced CO oxidation activity. For example, the reaction rate (ξ) at 30 °C for CO oxidation over Au/TiO2-PC was about 5.8 times greater than that over Au/TiO2-C for an anatase-to-rutile ratio of about 4:6, which was primarily caused by the more active gold species on the surface of TiO2 support in Au/TiO2-PC due to the Coulomb interaction during plasma preparation.