Catalytic Nanoreactors of Au@Fe3O4 Yolk–Shell Nanostructures with Various Au Sizes for Efficient Nitroarene Reduction

Abstract

Au@Fe3O4 yolk–shell nanocatalysts based on the thermal decomposition of iron pentacarbonyl in the presence of 2.5–10-nm Au core nanoparticles were successfully fabricated for the catalytic reduction of nitroarenes. The particle sizes of the Au@Fe3O4 nanostructures were in the range 8–15 nm, with Fe3O4 shell layer thicknesses of 2.0–2.4 nm. The Fe3O4 layer not only can form a magnetic shell for recovery but also enables the protection of the catalytic activity of the Au core nanoparticles toward the reduction of nitrobenzene derivatives including 2-nitrophenol, 4-nitrophenol, 4-nitrotoluene, and 1-chloro-4-nitrobenzene in the presence of NaBH4. The catalytic performance of Au@Fe3O4 is highly dependent on the particle size of the Au core materials and the substituent groups of the nitroarenes. The reduction rates of nitroarenes with electron-withdrawing groups were found to be 2.3–2.6 times higher than those of nitroarenes with electron-donating groups. In addition, the reduction of nitroarenes by the Au@Fe...