Abstract: A series of Au/Fe-O catalysts have been prepared by a co-precipitation method from a mixture of HAuCl4\54H2O and Fe(NO3)3\59H2O. These catalysts exhibit good catalytic activity for CO oxidation. The most active catalyst has 100% CO conversion at room temperature. The calcined catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). TEM observations reveal a homogenous distribution of gold particles between 10 and 15 nm on the iron oxide support. XPS results show that partially oxidized gold species exist in these samples. The difference in binding energies of Au 4f between these samples and bulk gold can be interpreted as that the Au 5d electrons partially flow into the Fe 3d orbit to some extent. So the attraction of nucleus in gold atoms is enhanced, resulting in the increase in the binding energies of Au 4f. This fact reflects that there exists an interaction between the gold nanoparticles and the support. For the CO oxidation on the 10～15 nm Au/Fe-O catalyst, the interaction between nanogold particles and iron oxide has more important influence on catalyst performance than the particle size of nanogold.

Key words: nanogold, iron oxide, supported catalyst, state of gold, carbon monoxide, catalytic oxidation