Synthesis and characterization of hollow ZrO(2)TiO(2)/Au spheres as a highly thermal stability nanocatalyst

A novel binary-metal-oxide-coated hollow microspheres-titanium dioxide-zirconium dioxide-coated Au nanocatalyst was prepared via a facile hydrothermal synthesis method. SEM, TEM, EDX, FTIR, XRD, UV-vis and XPS analyses were employed to characterize the composition, structure, and morphology of ZrO₂-TiO₂ hollow spheres. The size of Au nanoparticles was found to be 3-5nm in diameter before being immobilized on the aforementioned mesoporous ZrO₂-TiO₂ layer and used as catalysts in the reduction of 4-nitrophenol to 4-aminophenol by NaBH₄. Compared with TiO₂/Au and ZrO₂/Au, ZrO₂-TiO₂/Au NPs showed a higher catalytic activity because of due to mixed oxide synergistic effect. Besides, the sample gets the highest thermal stability and reactivity at 550°C, after calcining the hollow ZT/Au NPs at 550°C, 300°C and room temperature, respectively. Finally, a possible reaction mechanism was also proposed to explain the reduction of 4-nitrophenol to 4-aminophenol over ZrO₂-TiO₂/Au catalyst.