Interfacial Activation of Catalytically Inert Au (6.7 nm)-Fe₃O₄ Dumbbell Nanoparticles for CO Oxidation

Au nanoparticles epitaxially grown on Fe₃O₄ in Au (6.7 nm)-Fe₃O₄ dumbbell nanoparticles exhibit excellent stability against sintering, but display negligible catalytic activity in CO oxidation. Starting from various supported Au (6.7 nm)-Fe₃O₄ catalysts prepared by the colloidal deposition method, we have unambiguously identified the significance of the Au-TiO₂ interface in CO oxidation, without any possible size effect of Au. In situ thermal decomposition of TiO₂ precursors on Au-Fe₃O₄ was found to be an effective way to increase the Au-TiO₂ interface and thereby optimize the catalytic performance of TiO₂-supported Au-Fe₃O₄ dumbbell nanoparticles. By reducing the size of Fe₃O₄ from 15.2 to 4.9 nm, the Au-TiO₂ contact was further increased so that the resulting TiO₂-supported Au (6.7 nm)-Fe₃O₄ (4.9 nm) dumbbell particles become highly efficient catalysts for CO oxidation at room temperature.