Au nanoparticles epitaxially grown on Fe_(3)O_(4)in Au(6.7 nm)-Fe_(3)O_(4)dumbbell nanoparticles exhibit excellent stability against sintering,but display negligible catalytic activity in CO oxidation.Starting from various supported Au(6.7 nm)-Fe_(3)O_(4)catalysts prepared by the colloidal deposition method,we have unambiguously identifi ed the significance of the Au-TiO_(2)interface in CO oxidation,without any possible size effect of Au.In situ thermal decomposition of TiO_(2)precursors on Au-Fe_(3)O_(4)was found to be an effective way to increase the Au-TiO_(2)interface and thereby optimize the catalytic performance of TiO_(2)-supported Au-Fe_(3)O_(4)dumbbell nanoparticles.By reducing the size of Fe_(3)O_(4)from 15.2 to 4.9 nm,the Au-TiO_(2)contact was further increased so that the resulting TiO_(2)-supported Au(6.7 nm)-Fe_(3)O_(4)(4.9 nm)dumbbell particles become highly efficient catalysts for CO oxidation at room temperature.
