Facile synthesis of novel cage-like porous Ag-decorated silica nanotubes with enhanced catalytic activity

Novel cage-like porous Ag-decorated silica nanotubes (silica-Ag NTs) were synthesized as the porous silica NTs were firstly synthesized using the silk fibroin nanofibers (SF NFs) as sacrificial template via the sol-gel route and then supported the in situ decoration of Ag nanoparticles (NPs) via the hydrothermal route to derive porous silica@Ag NTs. SF NFs were prepared by electrospinning the SF solution via an electrospinning method, and then supported the self-assembly and packing of silica nanospheres when soaked in the Stifober-tye sol-gel system consisting of tetraethoxysilane, water, ethanol and ammonia, and finally removed by calcination to produce the porous silica NTs. TEM and SEM observations indicated that the resultant silica NTs presented cage-like and porous hollow structure with controllable pore size from 139 +/- 11 rim to 209 +/- 64 nm. They induced the deposition of Ag nanoparticles (NPs) with the diameter of 5-10 rim when hydrothermally treated in the solution of AgNO3 and played the reduction role in the, conversion of AgNO3 to Ag NPs. When exposed to, the 4-nitrophenol/NaBH4 solution, the resultant porous silica-Ag NTs showed catalytic activity. for conversion of 4-nitrophneol to 4-aminophenol.