Facile fabrication of superparamagnetic coaxial gold/halloysite nanotubes/Fe_3O_4 nanocomposites with excellent catalytic property for 4-nitrophenol reduction

摘要

A novel superparamagnetic gold/halloysite nanotubes/Fe_3O_4 (Au/HNTs/Fe_3O_4) nanocomposite with coaxial structure was designed and fabricated by selective decoration of the inner lumen and the external wall of halloysite nanotubes (HNTs) based on the difference inside/outside surface charges. The structure and composition of Au/HNTs/Fe_3O_4 were characterized by transmission electron microscope, powder X-ray diffraction, and X-ray fluorescence. The results indicated that Au nanorods selectively generated within the lumen of HNTs, while Fe_3O_4 nanoparticles uniformly deposited on the external wall. It was particularly worth mentioning that the structure of HNTs was not destroyed in the preparation process of Au/HNTs/Fe_3O_4 nanocomposites. The catalytic activity of the as-prepared Au/HNTs/Fe_3O_4 was investigated for the reduction of 4-nitrophenol in the presence of NaBH_4. The Au/HNTs/Fe_3O_4 nanocomposites exhibited excellent catalytic activity and cycling stability according to the kinetic data of the catalytic reduction reaction. In addition, the Au/HNTs/Fe_3O_4 catalysts can be easily manipulated by an external magnetic field for recycling.