This work explores the size-effect of zirconia nanoparticles on the catalysis of Au/ZrO₂ for CO oxidation. Zirconia particles with different sizes (ZrO₂-CP: 40～200 nm; ZrO₂-AN: 18～25 nm; ZrO₂-AD: 10～15 nm) was prepared from a single source of ZrO(OH)₂ and the deposition-precipitation method was employed to prepare the Au/ZrO₂ catalysts. The samples were characterized with XRD, TEM, XRF and nitrogen adsorption measurements. While the Au particles in all the Au/ZrO₂ catalysts appeared to show similar sizes (4～5 nm), the catalytic activity order of Au/ZrO₂-AD＞Au/ZrO₂-AN＞Au/ZrO₂-CP revealed clearly that smaller zirconia nanoparticles led to Au/ZrO₂ catalyst with higher catalytic activity. The activity improvement by reducing zirconia nanoparticle size seems attributable to the increased Au-zirconia junctions in the catalysts.

Key words: Au catalyst, CO oxidation, zirconia nanoparticle, nano-size effect, catalyst characterization