Superparamagnetic sandwich structured silver/halloysite nanotube/Fe3O4 nanocomposites for 4-nitrophenol reduction
Superparamagnetic sandwich structured silver/halloysite nanotube/Fe3O4 (Ag/HNT/Fe3O4) nanocomposites were fabricated by selective modification of the lumen of halloysite nanotubes with silver nanorods and the external wall with Fe3O4 nanoparticles. The silver nanorods within the lumen of halloysite nanotubes and the uniform Fe3O4 shell on the external wall were confirmed by transmission electron microscopy. The Ag/HNTs/Fe3O4 nanocomposites exhibit excellent catalytic activity and recyclability for the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. In addition, the nanocomposites show high efficiency in magnetic separation due to the high saturation magnetization and superparamagnetism. Therefore, the nanocomposites have great potential application in the catalytic field as recyclable and low-cost catalysts.